I don't want TRH thanks but if one of these points you in the right direction and they play WoW feel free to gift it to them
Starting at the top:
You didn't mention if you updated your graphics drivers from Windows update or manufacturer's site.
(sorry if you already said it and I missed it)
http://sites.amd.com/us/game/downloa...n_win7-64.aspx
Did you first completely remove your existing gfx driver installation and re-install the latest or did an "in-place upgrade" ie let it run on top of old.
If you didn't a complete driver uninstall take the time to do so.
Before linking relevant topics from all over the net
(the fact that I can find so many already hints at the source of the problem)
my guess (and at this point I don't think anyone can do more than guess)
is that
you have a defective graphics board on your hands (ie hardware problem).
Now to the linking:
Window7 Home 64bit, Radeon user, identical problem, US WoW forums:
http://forums.worldofwarcraft.com/th...09093987&sid=1
Tom's Hardware
http://www.tomshardware.co.uk/forum/...5970-nightmare
AMD's Forums (1)
http://forums.amd.com/game/messagevi...hreadid=123928
AMD's Forums (2)
http://forums.amd.com/game/messagevi...hreadid=131483
3D Guru's Forums
http://forums.guru3d.com/showthread.php?t=313754
I have to say that it just looks like a gfx card issue.
Suggestion would be to pursue an RMA if guarantee covers it.