Have you posted a question on Blizzard's tech forums, or looked there? If I have an issue that I can't resolve, I try and post there. The people can be helpful. Also, I'm sure this isn't the case but are you sure you have the ports opened that WoW uses? Also, you might have to run as administrator as well.
I'm just giving things that I do if I'm experiencing a hang-up on WoW.