Some say the Service Pack 2 Windows Update caused the black background problem with Microsoft Windows 7, but Microsoft is denying this. It isn't happening only with Windows 7 either, but also Windows XP and Vista. Some people say it happens to those that upgrade from Windows XP or Vista to Windows 7. Malware could also be the culprit. Whatever the reason a system restore should fix the problem.
Probably the easiest way to fix the black screen problem is to do a system restore. For most people this problem started after a Windows update. By doing this you will bring your system back to before you ran the update. To do a System Restore:
Reboot your computer and tap F8 as it is booting up. This will give you the option to put your computer into Safe Mode.
Type restore into the Start menu search box. Click on System Restore at the top of the Start menu.
The Restore system files and settings dialog box opens. You have the option to choose recommended restore, which will undo the most recent update, driver, or software install, or choose a different restore point.
If you choose the different restore point option make a choice from the list of restore points
Choose the restore point and confirm. Restart your computer and it will restore your system to the time you chose.