If you think it's a virus: midsail's advice is pretty good, actually. That's the best, and probably the easiest, to do. That is- if you can get to your laptop's HDD without destroying the thing. (In my experience, you won't have that problem with a Compaq.) If you don't have an external enclosure, you can buy one for ~$30-50, or you can buy an adapter set which will do the same thing but won't protect the drive. (That will set you back about $20 including shipping.) It's best to get one that will support 2.5" and 3.5" SATA or IDE drives for input, and USB for output. (eSATA is nice if you have it on your machine, but it's not common and isn't worth the trouble in my opinion.)
If you can't access the drive: Try to use some sort of bootable Antivirus program, such as
Avira AntiVir's Rescue System,
Dr. Web LiveCD, or
INSERT (w/ Clam Antivirus).
If you think it's a bad/corrupted antivirus install: Try to uninstall the program in safe mode using a third party tool, such as
CCleaner. If you're unable to uninstall it, at least disable it in startup. (Also done in CCleaner, but you can do it with the run command "msconfig" as well.)
Another option for both problems would to try to do a System Restore in safe mode. This will revert your operating system to a previous state- hopefully to a point BEFORE you had the antivirus software installed.