Okay, I have no idea if this can be used for anything at all, thought I'd post it though..
Allright, so I was screwin' around with my model edits, just made a new one and went to WoW to try it out when I got this message:
"You account is authorized for the Wrath of the Lich King expansion, but the computer you are playing on does not contain Wrath of the Lich King data. To play on this machine with this account, you must install the Wrath of the Lich King. Additional data is available at:[www. wow-europe. com/en/lichking/download/]"
Return to Login | Exit Game
So I thought it was kinda wierd, relogged, closed and opened WoW and nothing happen'd. I then saw I had the MPQ editor open, selected to the lichking.MPQ-file.. So I guess when it's already opened in one program it can't be opened in the other one too, tried to close it, log onto WoW and it worked smoothly, tried to open the file while I was in-game and it gave some error.. I guess the same goes for the expansion.MPQ..