flicker with more wow clients

hello,
when i start more then one wow client my screen starts to flicker.
the textures starts to flicker or changes the color for a second.
my old system dont have these problems.
first i thought the reason is the same directory, but a second/third etc. didn't help. after that i copied exact the same graphicsettings of my old system, also fickered.
then i flashed the gpu bios again with the standard clocks, also fucking flickering.
and yes i have dx9 and actuell graphic drivers.
please help me and sorry for my bad english, i hope someone can help me :>

my hardware beforce somebody asks:
intel c2d e8400 @ 4ghz
gforce 8800 gts 512mb @ 770/1875
4gb ddr ram (3,25 in xp)

greetz

omg i solved the problem with just starting wow in opengl, no fucking flickering anymore kthxbye

this might help as well:
wow in-game graphic detail macros (helps performance)

I got this same problem after i updated my geforce nvidea drivers to the latest...

flickering and distortions.
went back to a stable nvidea forceware i used before, and the problems were gone

new isnt always better