Re: WoW Problem, Anyone?
Is your system blocked behind a firewall? Are the correct ports open or forwarded?
Disable all your mods as Zeta mentioned and see if the problem occurs. Then re-enable half of them and see if it's ok. Narrow it down from there with half of the half each time until you isolate the problem.
Make sure nothing is running in the background while running WoW, especially Bittorrent.
Have you cleaned up and defragged your hard drive since WoW has been installed?