The problem is that I have just installed a new hard drive on an Acer Aspire 5135. Now, when I switch it on all I'm getting onscreen is OPERATING SYSTEM MISSING. All this when cd rom is set as boot drive and windows xp professional is in the drive. So can you help?

Have you reinstalled all drivers for your computer from acers website? The onscreen notification is not a windows feature, it was part of acers drivers, or software.

The BIOS in the ACER determines the maximum size of the hard drive it can support.
Check the laptop's specification to see the max size you can install in this model laptop.
It appears that the max size your laptop can support is 140 Gb (unformatted). 137Gb formatted.

I suggest you install a hard drive up to 140 Gb capacity in your laptop and place the 320 Gb hard drive in an USB hard drive adapter case and when you attach this hard drive to the USB port in your ACER laptop then you will be able to get the full 320 Gb capacity after you delete the partition and create a 320 Gb partition and format the hard drive.

It sure sounds like a problem with the hard drive. Acers usually don't include diagnostic tools to check it out, but that is what I would do next. If you don't know how to proceed, use a hard drive diagnostic like DFT to diagnose the hard drive.
visit http://www.hitachigst.com/support/downloads/
to get the info and download the DFT program. This will work on non-Hitachi drives as well, so don't worry about what type of drive is in your Acer.
If the drive is bad, it is a fairly simple matter of installing a new hard drive and reinstalling windows onto it. It's hard to say if the data on that drive is recoverable or not.

You need to format your hard disk. Please note that formatting will erase all you data from the hard disk and all the software including the Operating system.

If you have your OS master CD you can insert it in the cd/dvd drive and restart the laptop. This will detect the OS CD and try to install it. In the installation process there is an option "Format your hard drive". You should select that option. Then it will format, mark the bad sectors, create a new boot sector and install the OS. You will be just fine.

when you turn the unit on hit Alt+F10. This will access the acer recovery partition from which you can restore. This is provided you didn't replace the Hard drive or wiped the drive yourself

HI

you could try pressing powere on key and F8 key on startup and hopefully it will take you into the repair options and try to use the last good known configuration

or the repair my computer
if this does not help or fix the laptop and you dont mind loosing all the data thay you have
personaly put onto it then you could try to press the power up key then straightaway press the
ALT+f10 KEYS both at the same time and this should take you into the factory restore options
then follow the onscreen instructions and it should take you back when the laptop was ist purchased and switched on

if this does not work then the hard drive may be corrupt or damaged
which normally means that it has to go back to acer for repair
or maybe a new hard drive cheap enough from ebay
and try to get hold of some factory restore disks from acer if you do not possess them
then fit the new hard drive normally located at the base of the laptop unless its a acer aspire one
and use the factory restore disks to reload the operating system


good luck

Hello,
This issue may occur if one or more of the following conditions exist:

• The basic input/output system (BIOS) does not detect the hard disk.
• The hard disk is damaged.
• Sector 0 of the physical hard disk drive has an incorrect or malformed master boot record (MBR).
  
  Note Some third-party programs or disk corruption can damage an MBR.
• An incompatible partition is marked as Active.
• A partition that contains the MBR is no longer active.

To solve this, try one or more of the following solutions:
Verify your BIOS settings.. Verify the computer's BIOS settings to make sure that BIOS lists and recognizes the hard disk.The documentation that came with the hard disk should aid you in doing so.

Use Recovery Console..Use the fixmbr command in the Windows XP Recovery (or relevant OS) Console to repair the MBR of the startup partition. Be sure that a virus isn't present on the system and that their aren't any hardware errors as this could prove fatal to your hard disk.

The windows operating system may be corrupted. Suggest you restore it as the simplest solution.
The Acer Aspire One has a hidden partition on its hard disk drive that contains installation images to restore the system operating system, applications and drivers to the factory defaults. Press Alt and F10 key together while the Acer logo is displaying as the system is powering up. This should enter Acer eRecovery Management. Follow the onscreen instructions to do the recovery.

Recovery procedure for Acer netbooks.

Important Information

The Recovery disc will help you to restore the hard drive with the original software content that was installed when you purchased your notebook. Follow the steps below to rebuild your hard drive. Your drive will be reformatted and all data will be erased. It is important to back up all data files before you use this option.

Restoration procedure:

1. Press the power button to turn the system on.

2. Select to boot from a USB optical drive. There are two ways to do this:

2.1. Press <F2> during the Power-On Self-Test (when the Acer logo is displayed onscreen after bootup) to enter BIOS Setup.

2.1.1. Select the Boot menu.

2.1.2. Refer to onscreen instructions to set the first device to any bootable optical disc drive.

2.2. Press <F12> during the Power-On Self-Test (when the Acer logo is displayed onscreen after bootup), and select the USB ODD from the list that appears.

3. Ensure the Recovery disc is in an external (USB) optical disc drive, and exit the boot selection menu, by selecting Exit Saving Changes from the Exit menu or pressing <F10>, or by pressing <Enter> as appropriate.

4. Select Exit Saving Changes from the Exit menu or press <F10>.

5. Follow the onscreen instructions to complete the installation process.

6. When you finish the recovery process, please remove the Recovery disc and insert the System disc again.

7. Restart your computer.

no it is not