Hey guys, every time I try to sign into MSN Messenger I get an error saying:

"We could not sign you in to MSN Messenger. It appears that you are behind a firewall that might be proventing you from connecting to the .NET Messenger service. 0x81000365"

I haven't got any firewall programs on my computer. Anybody got any ideas what's going on, or how I can fix it? Cheers.