I have apple software update on my computer. I used it to download itunes + quicktime 8.2.1. It had a problem and a window came up saying to select download only. Well, I did and it's done. But now it says select the item you want then install. There's no install button!

try to uninstall all apple software from your computer

e.g. iTunes, Quicktime, bonjour etc.
delete temp files
click start > run > cmd > type "%temp%" without the double quotes
then select all files then delete all of them

restart the computer

try to download and install Itunes
if still doesnt work

download CCleaner to remove all traces of apple/itunes from your computer then restart and reinstall after restart.

hope this help

Please take note that the following steps is in assumption that you are using a Windows operating system.) As I have found out in the iTunes support in apple.com, this symptom may be caused by anti-spyware software preventing iTunes from installing correctly. One such application is SpyCatcher. Before installing iTunes, temporarily remove this software to allow the iTunes installer to complete.

If you are still having trouble installing iTunes for Windows, follow the troubleshooting suggestions described in this article.

General installation troubleshooting Important: iTunes installation is successful a majority of the time after completing these troubleshooting procedures. If one step does not resolve your issue proceed to the next.
1. Empty your Temp directory and restart
Windows XP:

1. Choose Start > My Computer (or double-click My Computer on the Desktop).
2. In My Computer or Computer, open the "C:" drive.
3. Open Documents and Settings.
4. Double-click the folder titled with your username.
5. If you see a Local Settings folder, skip to step 10. If you don't see a Local Settings folder, proceed to the next step.
6. Choose Tools > Folder Options.
7. Click the View tab.
8. Select the option to "Show hidden files and folders."
9. Click OK.
10. Double-click Local Settings.
11. Right-click on the Temp folder and choose Delete.
12. In the confirmation dialog that appears click Yes.
13. If you are unable to delete the Temp folder, close all programs, especially those in the Notification area ("System Tray") of the Windows Task bar and repeat step 11.
14. Restart your computer.

Windows Vista and Windows 7:

1. Choose Start > Computer
2. In Computer, open the "C:" drive.
3. Open the Users folder.
4. Double-click the folder titled with your username.
5. If you see an AppData folder, skip to step 10. If you don't see an AppData folder, proceed to the next step.
6. Choose Organize > Folder and Search Options.
7. Click the View tab.
8. Select the option to "Show hidden files and folders." (In Windows 7 this option will be called "Show hidden files, folders, and drives").
9. Click OK.
10. Double-click the AppData folder to open it. If Windows needs your permission to continue click Continue.
11. Double-click the Local folder to open it.
12. Right-click on the Temp folder and choose Delete.
13. In the confirmation dialog that appears click Yes.
14. If you are unable to delete the Temp folder, close all programs, especially those in the Notification area ("System Tray") of the Windows Task bar and repeat step 12.
15. Restart your computer.

2. Completely remove iTunes and QuickTime
For Windows XP, follow instructions in Remove and Reinstall iTunes, QuickTime, and other software components for Windows XP.
For Windows Vista or Windows 7, follow instructions in Remove and Reinstall iTunes, QuickTime, and other software components for Windows Vista.
Note: Songs you purchased from the iTunes Store or imported from CDs are saved in your My Music folder by default and are not deleted by removing iTunes.
3. Install the latest version of iTunes
Once you have completed the above steps to Empty your Temp directory, Completely remove iTunes and QuickTime, and Clean up iTunes installer files on the computer, you can install the latest version of iTunes from http://www.apple.com/itunes/download.
Additional troubleshooting Make sure you have administrator-account access To install iTunes or QuickTime software, you need to be logged in as an administrator on the computer. If you're not sure if you have administrator-account access, contact the owner of the computer or your system administrator.
Get the latest Windows updates The first thing to do when troubleshooting an installation issue on a Windows computer is make sure you have the latest Microsoft Windows updates installed—to get the latest updates, go to the Microsoft Windows Update page.
iTunes and QuickTime software for Windows require Microsoft Windows XP or Microsoft Windows Vista with latest Service Pack installed.
Disable other conflicting software In Windows, some background processes can cause issues for other programs and processes. These conflicts can prevent applications such as iTunes and QuickTime Player from installing. See Using MSCONFIG to troubleshoot conflicts in Windows XP or Using MSCONFIG to troubleshoot conflicts in Windows Vista and Windows 7 for assistance disabling conflicting processes.
Additionally, some third-party security software cannot be disabled using Selective Startup (MSConfig). Because of this, it may be necessary to temporarily manually disable such software while troubleshooting installation. For assistance in configuring or disabling your security software, please contact the manufacturer.
Make sure your folder names don't contain strange characters If the iTunes installer (iTunesSetup) is not responding or appears frozen after launching the installer then the folder where the installer is stored may contain unusual characters. If you notice that the iTunes installer or stored in a folder like this, either rename the folder or move the iTunes installer to another location such as the Desktop before launching.
More help If these steps don't help, you may be able to find a solution to your issue by searching the Microsoft support website.
If the above troubleshooting steps have not helped, proceed to the following steps Solutions to common installation errors Here are some common symptoms you may see when installing iTunes and QuickTime for Microsoft Windows. If you are experiencing one of these symptoms, try the suggested troubleshooting steps:

• iTunes and QuickTime for Windows XP cannot be installed without Visual Basic Script (VBScript)
• iTunes for Windows: "Disk is locked" or "iTunes folder cannot be found" when installing or opening iTunes
• iTunes 7 or later for Windows Installation stops responding while "registering modules"
• QuickTime or iTunes Installer "Could not open key" alert stops install on Windows
• iTunes: Windows reports that iTunesSetup.exe is not a "valid Win32 application"
• "Bonjour service failed to start, verify you have sufficient privileges" error message when installing

If you only need to install QuickTime, or if iTunes installs but QuickTime installation did not complete Try downloading and installing the standalone version of QuickTime from http://www.apple.com/quicktime/download/. Be sure you download the version that does not include iTunes.

Learn how to completely uninstall iTunes, QuickTime, and other essential software components from your Windows XP PC.
How ToFor Windows Vista or Windows 7, see this article.
Expand All Sections | Collapse All Sections
In some rare instances, it may be necessary to remove all traces of iTunes, QuickTime, and related software components from your computer before reinstalling iTunes.
Use the Control Panel to uninstall iTunes and related software components in the following order:

1. iTunes
2. QuickTime
3. Apple Software Update
4. Apple Mobile Device Support
5. Bonjour
6. Apple Application Support (iTunes 9 or later)

Important: You may see various alert messages if you uninstall these applications in a different order or only uninstall certain components.
For detailed steps on removing and reinstalling iTunes and related components on Windows XP, refer to the following steps:
Removing iTunes Note: iTunes Store purchases or songs imported from CDs are saved in your My Music folder by default and are not deleted by removing iTunes.

1. Quit iTunes.
2. From the Start menu, choose Control Panel.
3. In Control Panel, open Add or Remove Programs.
4. Select iTunes from the list of currently installed programs, then click Remove.
5. When asked if you would like to remove iTunes, select Yes.
6. After the uninstallation is complete, do not restart your computer if you are prompted to.
7. If other program entries were listed for iTunes in Add or Remove Programs, remove those as well.
8. In Add or Remove Programs, remove any iPod Updater applications that are listed in the same fashion as iTunes was removed.

Removing QuickTime

1. Quit QuickTime Player.
2. From the Start menu, choose Control Panel.
3. In Control Panel, open Add or Remove Programs.
4. Select QuickTime from the list of currently installed programs, then click Uninstall.
5. When asked if you would like to remove QuickTime, click Yes.
6. After the uninstallation is complete, do not restart your computer if you are prompted to.
7. If other program entries were listed for QuickTime in Add or Remove Programs, remove those as well.

Removing Apple Software Update

1. Quit Apple Software Update.
2. From the Start menu, choose Control Panel.
3. In Control Panel, open Add or Remove Programs.
4. Select Apple Software Update from the list of currently installed programs, then click Uninstall.
5. When asked if you would like to remove Apple Software Update, click Yes.
6. After the uninstallation is complete, do not restart your computer if you are prompted to.
7. If other program entries were listed for Apple Software Update in Add or Remove Programs, remove those as well.

Removing Apple Mobile Device Support

1. From the Start menu, choose Control Panel.
2. In Control Panel, open Add or Remove Programs.
3. Select Apple Mobile Device Support from the list of currently installed programs, then click Uninstall.
4. When asked if you would like to remove Apple Mobile Device Support, click Yes.
5. After the uninstallation is complete, do not restart your computer if you are prompted to.

Notes: Do not manually delete the Mobile Device Support folder located at C:Program FilesCommon FilesApple. Use Add or Remove Programs as described in the steps above.
Removing Bonjour

1. From the Start menu, choose Control Panel.
2. In Control Panel click "Add or Remove Programs."
3. Select Bonjour from the list of currently installed programs then click Uninstall.
4. When asked if you would like to remove Bonjour click Yes.
5. After the uninstallation is complete do not restart your computer if you are prompted to.

Removing Apple Application Support (iTunes 9 or later)

1. From the Start menu, choose Control Panel.
2. In Control Panel, open Add or Remove Programs.
3. Select Apple Application Support from the list of currently installed programs, then click Uninstall.
4. When asked if you would like to remove Apple Application Support, click Yes.
5. After the uninstallation is complete, do not restart your computer if you are prompted to.

Verify iTunes and related components are completely uninstalled

1. Restart your computer.
2. After the computer restarts, open Local Disk (C:) located in Computer or whichever hard disk your programs are installed on.
3. Open the Program Files folder.
4. Right-click the iTunes folder, choose Delete, and choose Yes when asked to confirm the deletion. Note: This folder may have already been deleted if iTunes was successfully removed.
5. Right-click the iPod folder, choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
6. Right-click the QuickTime folder (if it exists), choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
7. Right-click the Bonjour folder (if it exists), choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
8. Open the Common Files folder.
9. Right-click the Apple folder (if it exists), choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
10. Open Local Disk (C:) located in Computer or whichever hard disk your operating system is installed on.
11. Open the Windows folder.
12. Open the System32 folder.
13. Right-click the QuickTime file (if it exists), choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
14. Right-click the QuickTimeVR file (if it exists), choose Delete, and choose Yes when asked to confirm the deletion. Click Continue if Windows needs confirmation or permission to continue.
15. Right-click the Recycle Bin and choose Empty Recycle Bin

Reinstalling iTunes and related components After verifying that iTunes is completely uninstalled, you should download and install the latest version of iTunes.
Additional Information iPodService.exe Alert Follow these steps if the message, "Cannot delete iPodService.exe: It is being used by another person or program" appears when you try to delete the iPod folder.

1. Make sure that iTunes and the iPod Updater utility are not open.
2. Press and hold Control-Alt-Delete. Select Start Task Manager.
3. Click the Processes tab.
4. Locate "iPodService.exe" in the list.
5. Click "iPodService.exe" and choose End Process.
6. Quit the Task Manager.

You can download the Windows Installer Cleanup Utility from Microsoft, which will clean up any leftover installer files that may be causing issues with your current installation. To do this:

http://support.microsoft.com/default.aspx?scid=kb;en-us;290301

Click the "Download the Windows Installer Cleanup Utility package now" link

-Choose Start > All Programs and then click Windows Install Cleanup; the Windows Installer Clean Up Utility window appears, listing software that is currently installed on your computer.

-Select iTunes from the list and click Remove.
-Click OK in the confirmation dialog that appears.
- if it prompts to restart - choose restart later

-Repeat this step for removing these progrmas as well in order

QuickTime
Apple Software Update
Apple Mobile Device Support
Bonjour
Apple Application Support (iTunes 9 or later)

-Click OK in the confirmation dialog that appears.

Click Exit.
Restart the computer.

download itunes again

http://www.apple.com/itunes/download/

A number of users have experienced problems updating to the newlyreleased iTunes 8.1.1. Generally, when this issue occurs, installationappears to proceed normally but then delivers the error message “Theinstaller encounted errors before iTunes could be configured. Yoursystem has not been modified. To retry these operations at a later timeplease return to the installer again. Click Finish to exit installer.”Fix
This problem can often be fixed by reinstalling the latest version of QuickTime via the following steps:

1. Download the latest edition of QuickTime for Windows (make sure to pick the option without iTunes)
2. Choose to save the file to your disk, then double-click the .exe file and install QuickTime
3. After QuickTime is successfully installed, download iTunes again, choosing to save the file. Double-click the iTunes installer .exe and proceed with installation.

Other potential fixes for this issue include:
Run a disk check Disk errors, particularly in Windows XP, can prevent proper iTunes installation. See this Microsoft Knowledge Base article for instructions on performing a disk check/repair.
Use Windows Installer Cleanup Use the Windows Installer Cleanup toolto remove any references to Apple-related installation files(QuickTime, iTunes, etc.), then re-try using the aforementionedtwo-step method to reinstall QuickTime and iTunes

Go to store at top and scroll to authorize computer this should solve problem

Go into control panel/add remove programs and make sure you remove any Apple remnants of programs. Do you have USB 2? I have had problems using mine on USB 1 as it was too slow. Hope this helps some.

Here's some info that may help - picked up from other boards where similar problems reported.
First check to see if Quicktime works normally, iTunes will not work without it.
If Quicktime is OK, then use these troubleshooting articles: XP version http://support.apple.com/kb/TS1421 Vista version http://support.apple.com/kb/TS1717
Have you installed any of the following: ACE & K-Lite mega codecs package, QT alternative, Storm codec, WinAVI video converter, Mpcstar, (possibly starcodec pack, 3ivx)
If so uninstall them, they are know to cause problems with Quickitme. Then download the version of Quickime without iTunes: http://www.apple.com/quicktime/download/win.html Now Remove Quicktime using the method for Quicktime in this article (just Quicktime): XP http://support.apple.com/kb/HT1925 Vista http://support.apple.com/kb/HT1923 When you come to your C:\Windows\system32\ folder you can delete any file or folder with Quicktime in the name. Restart you computer Install the stand alone Quicktime and check if it starts. If it does you are in a position to find out if iTunes is OK.
If Quicktime is OK, do you get any error message when you try to start iTunes? If not, open your task manager after trying to start iTunes. Do you see iTunes.exe running on the processes tab. If there is no error and you see iTunes.exe running then iTunes is hanging and we need to look at a slightly different route.

Sometimes it is just a problem with the itunes database file when it won't open after an upgrade. Press and hold the shift key while trying to start itunes. Does it give you an option to choose or create a new library? http://docs.info.apple.com/article.html?path=iTunesWin/8.0/en/15502.html

Bonjour is a common cause of iTunes hanging at start up. i.e. silent launch failure with iTunes.exe running on the processes tab. You can uninstall bonjour if you don't need it. However it is required for sharing libraries and other things
You could also try uninstalling it, then downloading bonjour from Apple and installing it directly. http://support.apple.com/downloads/Bonjour_for_Windows

Try uninstalling iTunes, Apple Software Update, Apple Mobile Device Support, and Quicktime. (Note: When you uninstall each of these, it asks whether you want to restart your computer. Say no until you have unnstalled the 4th one, after which restart your computer).
Then, reinstall iTunes. It should work.