shut the power down if you haven't already. i'm using guess work, but it can't hurt.
find a computer consultant that will come to the house for about $100.00 an hour. you need to have one of these know it guys that you can call occassionally.
my guru moved to another state, and until i found a new guy, i had a virus in one computer that i couldn't get rid of.
like any other service guy, the electrician, the washing machine repairman, etc, the only real way you will know if he is any good, is if the problem gets solved.
i suspect you are going to have to reinstall windows. anything less will be a bonus. you should have something like norton ghost back up or anything similar to back up to a cd in the future, so you are not f'd again.
if some one can develop a program, someone else can figure out how to vandalize it and your computer.