"Unable to validate game version. This may be cause by file corruption or the interference of another program. Please visit http://www.worldofwarcraft.com/support for more information and possible solution to the problem."
There's a patch you need to download. It needs to say version 0.9.1 at the bottom left hand corner. When you unzip the file make sure you put it into your WoW directory, run the patch and you're good to go. Patch is like half a meg.