I have this problem when I used Windows Live Messenger (not plus) where often when it connects it gets in and shows my entire contact list then when I try to talk to someone they don't respond because they're not actually getting my messages because I'm not actually connected, then eventually it disconnects and tries to reconnect.

Whenever this happens the entire internet stops working on my computer.  I had a friend over the other day and he connected as well and whenever either of us tried to connect to msn and got this problem it would disconnect the others internet as well.

I'm behind a wireless connection and a router.  What port exactly does windows live messenger use? I could try opening that port and see if it fixes the problem.

What is most strange is that it doesn't happen all the time but most of the time.  I don't think it's a wireless problem either because it did it on another computer which is just straight into the router.

Could be due to firewall problems...

Well there's a firewall built into the router I think.  What port do I open up?

Bump?

That's I can't tell u but I am sure about that the firewall is the problem a friend have had said that to me, n he have had the same problem!