Try to get a complete backtrace. Maybe https://wiki.ubuntu.com/X/Backtracing can be of help.
i'm running the latest git (X, mesa, drm, radeon driver) on an x1300, and it works great - compiz works fine as do most 3D apps. however, sometimes when i restart X i get this message in Xorg.0.log:
the backtrace is always the same, but i don't know what the problem could be. any way i could help? anyone get anything similar?Code:Backtrace: 0: X(xf86SigHandler+0x7d) [0x80cabca]