ADinf Anti-Virus Software
This is a shareware program (with a nominal cost after the first 30 days) that you use along with virus-protection software. It takes snapshots of your computer and compares them to prior snapshots. This would be very handy if your computer suddenly started to misbehave. Be sure to check this tool out.
Needless to say, try any software from this list at your own peril, and remember that it's always a good idea to backup your system before installing anything new. There are lots informative sites listed here, but if you know of any other good ones, please contact us.