Screen corrupted every 215th pixel

[Oldřich Jedlička]

Hi all,

I have a really strange problem. I have every 215th column (in pixels) 
corrupted - when I draw two vertical lines with 214 pixels in between in Gimp 
and move the window on the desktop to the specific position, I don't see any 
line (the column is filled with the background color). I see the problem in 
both KDE applications and in Gimp (Gtk application), so I think this isn't a 
toolkit problem. When I move any window, I see something like "missing" 
columns clearly (text has no vertical line, icons miss/repeat one column).

It starts on the 214th column (counted from 0) and after every 215 pixels I 
see the problem.

I cannot attach a screenshot, because screenshot taken with Ctrl+Printscreen 
shows no problem. 

It looks like the screen is split into stripes with 215 pixels (plus minus 
pixel) and every one has somethinh like off-by-one problem.

I'm using this software:

xorg-server-1.9.2.902
mesa Git master (r600 gallium driver)
libdrm Git master
xorg-video-ati Git master
kernel 2.6.34-rc5, drm-next branch from airlied/drm-2.6.git
qt-4.7.1
kde-4.6-rc1
gtk+-2.22.1

Does anybody know where the problem could be?

Thanks,
Oldrich.