I've found AIM to be vulnerable to viruses, trojans, things like that. Thats why I use pidgin myself, heres it's site:
http://www.pidgin.im/
As far as AIM viruses go, you might want to quit using AIM, and then check your processes. If you're not sure what one is, google it. Odds are that people have already identified the process, and all you need to do is find the one people scream virus.
A couple years ago I got the virus, and I used the virus clean from jayloden.com without much trouble.
Best of luck.
__________________
Be Healthy. Never Stop Learning. Say It Like It Is. Own It.
Like our values? Flexware Innovation is looking for Automation Engineers. Check us out!