Scenario 4: A blue screen or BSOD appears

Diagnosing blue screen or BSOD involves methodical troubleshooting. A BSOD can be caused by both hard- or software problems. Consider which is most likely in this section of our repair guide. If it is likely a hardware problem, check our hardware troubleshooting guide. If you suspect a software problem, usually it will cost you less time to just reinstall Windows instead of trying to repair it. If you do think it is a hardware problem, refer to our hardware problem module.

Before reinstalling you can try to press F8 during startup (you might have to press it multiple times to get into the menu)

You will enter the safe mode menu: http://support.microsoft.com/kb/315222

After pressing F8, select “Last Known Good Configuration: This option starts Windows by using the previous good configuration.”

If that does not work, try “Safe Mode (SAFEBOOT_OPTION=Minimal): This option uses a minimal set of device drivers and services to start Windows." If your windows does not even boot into safe mode it is probably easier to just reinstall it.

To use system restore, check this article (ignore the first paragraphs and scroll all the way down to “Use System Restore”

To troubleshoot the BSOD instead of simply reinstalling windows: http://www.hardforum.com/showthread.php?t=968407