Hello,
I been playing WoW since its first release and I would like to suggest first, go to their website
http://forums.worldofwarcraft.com/
They are usually very quick about responding.
Also, you say you have your friends copy and that is doing the same thing? Is your computer spec'ed for gaming? What kind of system, what video card are you using, what operating system are you using and how much ram? World of Warcraft requires a lot of high end gear in order to run efficiently.
I have heard of a boot-leg protection that WoW has incorporated into their software to prevent hacking, hopefully your copies are clean?
Morriah