Apparently there is a secrurity flaw in AIM that could allow a worm to affect your system ,here are the details:
If you use AOL Instant Messaging, Please take the following action: (as soon as you can)
1. A temporary solution to this vulnerability is:
1. Go to your Preferences
2. Go to the Privacy section
3. Click "Allow only users on my Buddy List" under "who can contact me"
This will disable the vulnerability because you will appear signed off to
anyone not in your buddy lists.