It sounds like a virus to me.
Might be a hardware issue as well.
Do you know how to boot to the BIOS?
Some machines will let you reset defaults from there.
If you can get it to boot at all, go to tools (in accessories I think for Win 7), and look for the restore button. Sometimes that will work, and it will boot using your last known good configuration.

If you know of a computer shop, or Best Buy in your area, that would be the best bet.

HTH,
Gary