WotLK Client won't start

Hello,
I am trying to start a WotLK client on a windows 7 x64 machine with a Intel Pentium G4600 processor and 8 gigs of ram.
But It doesn't work. Nothing happens when I use WoW.exe, the only thing I can see is there are two processes started (seeing them in Task Manager) :
1. WoW.exe *32
2. Rundll.exe *32

rundll.exe skyrockets my processor to 100% on all 4 cores and stays like that untill I kill the process. When I run WoW.exe in Windows xp competability mode I get better proccessor results ~50% on all cores, but still - no client is being loaded. I did try to disable antivirus software for testing purposes, but to no avail.

Does anyone have any idea on what could be the issue?

try this:
1) Restart your PC
2) close your Torrent client and move your WoW folder away from your Torrent's download destination
3) now right click on WoW folder> Properties> remove "read-only"

Unfortunately I had all of this done even before posting my question :(. Thank you for your reply, tho. Got any more ideas?

try to download the client again? but this time pick "wotlk (old)"

Old client downloaded and working. Interesting. Well, I guess the case is closed. Thank you.