My acer aspire goes to the bsod and says unmountable boot device.I've tried to restore windows 7 but it freezes and so does safe mode. I have ubuntu installed and I can access files on the harddrive. Any ideas about this message and how to fix it. Before I started getting this message, windows was running really slow

Depending on your version of windows, I would trying starting in safe mode to see if the computer does boot. If it does, then you want to restart again, go to advanced boot options and select "start windows with last known good configuration." Access advanced boot options following the steps at this link. Need to Start Windows 7 in Safe Mode Here How

Please contact acer and ask for operating system disk.

You may have a corrupted video driver due to an update. For some Acers, press and hold F10 when starting the computer. Two beeps will mean that the bios settings have been restored and the machine may boot correctly. If you can enter the BIOS via F2, F1, F10, ESC or DEL, then find the area for display and change it to low resolution then save and restart your computer. Once running, you will need to uninstall the current video driver and have the computer install a new one.

Try a System Restore and select a restore date before your problems started.
To get to the System Restore - Click on Start - All Programs - Accessories - System Tools - System Restore

Switch ON the PC, boot the PC in 'Safe Mode' by continuously tapping F8 button after you switch On until you get the Safe Mode Option.

Let windows boot in Safe Mode and log in to windows.

1. Open the Start Menu.

A) Click on All Programs, Accessories, System Tools, and System Restore.

2. Open the Control Panel (All Items View).

A) Click on the Recovery icon.
B) Click on the Open System Restore button.

A 'System Restore' window will appear. Here you will have to check "Restore computer to an earlier time'

A) Click on the Next button

Now you will find a window with Dates, Description and Type,

Note: It is better if you could remember from which date you are facing the issue, try to select a date prior to that date.

The detail of that particular date should show "System Checkpoint" and time on the right hand side box. Select that date.

Now, Click on Next and System Restore will start. Click on the Finish button and windows will take a reboot.

Windows is probably getting stuck on start-up and this is likely due to a driver problem. The presence of a blue screen with the mouse pointer icon on it has a description called BSOD (Blue Screen Of Death). BSOD was common in earlier Windows versions as they were not robust enough to withstand misbehaving applications. Current Windows better isolate applications so that BSOD does not occur but it can still happen during the start up process. My suggestion is that you should try running Safe Mode then do a System Restore to an earlier date when the system used to start properly. Strongly suggest that you have the system plugged into its AC adapter before doing this. The following is based on Windows XP (you didn't indicate what O.S. you had).
1. do a power-on and press F8 repeatedly to get the Windows Advanced Options Menu
2. use the up-down arrow keys to highlight Safe Mode and press the Enter key
3. on the Windows log-in screen, click your user name icon to log-on
4. on the Desktop window, click the No button to indicate a choice to use System Restore
5. on the Taskbar, click on the iconized System Restore to open the System Restore window
6. click the Next button to get the Select a Restore Point window with the monthly calendar
7. on the calendar, click a bold date then click the Next button
8. on the Confirm Restore Point Selection window, read and if it is OK click the Next button
9. during System Restore, the system will be shut down and restarted. Let this proceed normally.

Its the problem with hardware driver software. Please remove last installed software/hardware in your system. To remove software run system in safe mode by pressing F8 on system starting and select safe mode then remove last installed hardware by opening device manager or remove software by opening add remove program from the control panel.Then restart system.
Any problem came ask again new question
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You can check your laptop further by booting it from Safe Mode. To boot your computer in Safe Mode, try to tap continuously F8 function key on your keyboard immediately when you start your computer. It will lead you to an Advanced Menu from where you can choose the option "Safe Mode" and hit enter to boot your computer to safe mode. Now try to check the display driver in the device manager (Control Panel >System > Hardware >Device Manager) If it is not there, try to reduce the screen resolution and reboot your computer to the normal mode. If you are still getting the blank screen in Normal mode, try to boot computer back in Safe Mode and try to restore your computer to earlier time when it was working fine for you. To do so click on Start Menu > All Programs > Accessories > System Tools > System Restore. On the Welcome to System Restore page, click Restore my computer to an earlier time (if it is not already selected), and then click Next. On the Select a Restore Point page, click the most recent system restore point in the "On this list, click a restore point" list, and then click Next. Now confirm the restoration and click on Next to complete the restoration and follow the wizard.
Cheers!

Try booting the thing in Safe Mode. Upon startup (after the Acer logo goes) press F8 several times. You will be offered a menu select Safe Mode (at the very top of the list). If the system reaches the desktop, you can repair your Windows. For the three fixes below you will need to go Start Menu>Run...
1) Write: fixmbr, and press ENTER.
2) Write: fixboot, and press ENTER.
3) Write: chkdsk, and press ENTER.
(The later will take several minutes, but you can read what stage it is doing).

Windows Boot Genius from http://www.windowspasswordsrecovery.com/windows-boot can help us fix problems quickly!