thats what you get for not running AV, lots of virus and worms will do their dammedest to damage or stop any popular antivirus running if you try to install it after you got infected, some even patch the AV so it thinks it`s working when its actualy just wasting your time doing nothing, you have no excuse, there are free firewall and antivirus programs out there, just install something like antivir and you get free updates and a virus scanner/monitor thats fairly good, I haven`t ever had a virus, and after finding out that antivirus like norton expires after a year I never bought another commercial offering, I ain`t paying £60 for a program that runs out after 12 months, they can go whistle, I run Kerio personal firewall and antivir and never had one infection, I update the definitions every day and scan twice per day (automaticly with the scheduler, does it when I go for dinner and finish work on the PC at 9:30), so I don`t get any real inconvenience, only thing you have to do is to turn off the scanner when you open a cd, or it trys to scan all the files on the cd for virus before it allows access.
Mentor.
http://www.free-av.com
(free for personal use..unlimited updates)
http://www.kerio.com/kpf_download.html
(free for personal use..DOES
NOT PROTECT NETWORKS..you need the commercial version for that)