In the TechDemo Map I am experiencing weird graphic bugs with colored triangles suddenly flash dependent on my player position.
LinuxMint 12x64 (Based on Ubuntu 11.10)BR
Software rendering with Intel i72600K Graphics ChipBR
Thanks for the screenshot.
I've never seen this before (using Windows or Ubuntu 11.10 with proprietary NVidia drivers), but it almost certainly looks like a bug in the graphics driver.
Alas, I've no idea what to do about it.