Ok heres the scenario:

I got a 10 pc network running behind a Dlink router conected to a 3mb/s cable conection and they're all configure with the same stuff/hardware/settings. 9 PC's are running everything ok, internet works just fine.

1 of them has a very peculiar problem. I can connect the ftp, I can browse the internet I can even post here via firefox/internet explorer. But, when it tries to connect messenger or gtalk it simply doesnt connect. I got no firewall on this pc right now, so nothing its blocking the service.

I reinstaled SP2, I did an upgrade with the windows xp cd and nothing...

I really dont want to format... grrr too many stuff to reconfigure and I dont have the time.

Do you got any ideas?
Thanks in advance.