A dark gray screen is NEVER caused by a virus. The virus wants you to keep using your computer as long as possible so it can work as long as possible.
You can go to the BIOS settings. Good.
Is the display correct when you are there? Is yes, then your screen is OK. Your video "card" is also working correctly.
If after that you can't boot to windows, it probably means some missing files like Bootfont.bin, NTDETECT.com, autochk.exe or ntldr.
All 4 are required for windows to even start loading.
When absent, you get a black/dark gray screen with a small flashing underscore character in the top left corner.
You probably need to reinstall windows. You need to assume that the reinstallation will irrevocably erase any data present on the drive.
If you have files that you want to keep:
Get a Linux live CD and use it to boot. You'll be able to access your files and copy them to some external drive or burn them to some CDR or DVDR, or even transfert them to another computer.
Reinstall and copy your files back.
Electro, May 2011
