I think I have the same problem here. I can connect to the icq server like normal. After a while I get a notification, that I was disconnected...some disconnections later I get the 10 minutes warning, that I connected to fast.
I am using Kopete 0.12 (also used the beta before with no problems) with KDE 3.5.3 on a Gentoo System. And yes, I am behind a router (linksys with newest dd-wrt).
All other stuff works like charm.