I can relate to computer problems when I upgrated from Windows 98 to XP!! What a mess.
Actually, what we found after trying everything was that one of the programs on my PC was conflicting with XP. You know what helped?

Go to start/run/msconfig

On the start-up, make sure there's not a checkmark next to Selective Start. Start your pc the normal way and see if that helps.

Your aol filing cabinet resides on AOL's server, not your PC. Once you get your PC working properly and are able to log on to aol normally, all your information should be there.

Let me know if this helps and happy holidays.