https://bugs.freedesktop.org/show_bug.cgi?id=32945
--- Comment #8 from Marek Olšák maraeo@gmail.com 2011-01-25 08:33:52 PST --- It appears that one third of the zbuffer is not cleared on your machine. In src/gallium/drivers/r300/r300_emit.c, can you add this line:
numdw = ALIGN_DIVUP(numdw * 3, 2);
at line 1171 and do some testing?
Could you also please attach your dmesg?