Disconnects and odd port #’s

For the past few weeks I have had constant disconnects on aim, before that I could stay on for days at a time. Also when I try to log back in some of my sns will and others wont. They get stuck at verifying name and password. The other weird thing is that alot of times I cant get connected or stay connected on port 5190 and so I do autoconfigure and it logs in on port 21 almost everytime.
i am behind a linksys router, but never had this problem before, I have port 5190 opened for aim, but it has made no difference. In fact both comps are having the same problem and the weird thing with the other comp is it will only log on with port 21 or port 13, when 5190 wont work.
Any ideas on this?
i have a firewall, antivirus, and do daily scans for trojans, adware, etc. im clean as far as I can tell.