http://bugs.winehq.org/show_bug.cgi?id=21043
--- Comment #17 from Roderick Colenbrander thunderbird2k@gmail.com 2009-12-22 12:16:51 --- There is one easy way to test where the problem is. The Nvidia drivers try to accelerate big parts of XRender using the GPU. If you add the line: Option "RenderAccel" "0" to the screen / device section of your xorg.conf the drivers will fall back to software XRender (which is also used by ATI and other drivers). I suspect the issue won't occur in that mode.