"Tip: If you are asking for help to troubleshoot a computer-related problem, please be sure to include all the necessary information (ie: operating system, model number, hardware, software, etc) that will help others identify your problem for a speedy resolution."

With as little as you provided, I can't guess what caused it.

AOL has free support, try them? They will ask many questions and help you out with the AOL issues.

If you want to continue, heed the Forum Tip, supply some history, what firewall you use, antivirus, spyware tools, versions of the OS (SP1, 2, 3, 4), the browser version and most important the ERROR and EventID that's in the EVENT VIEWER.

Don't know the EVENT VIEWER? It's noted in Start, Help as well as google.com