If it suddenly started and downgrading doesn't help, have you ever considered your hardware to be broken?
That means your GPU is hung. So instead of spreading bad publicity in a forum not read by intel employees, you could do:
1. Install kernel 2.6.34 (needed for debugging)
2. install intel 2.11.901 + libdrm-??.21
3. When a hang occurs, log in via ssh save the GPU-state as well as the last batchbuffer. File a bug at freedesktop's bugzilla, and append those files:
I guess they would be more than happy about feedback like this.After a freeze, can you grab a copy of dmesg, Xorg.log, intel_reg_dump,
and /sys/kernel/debug/dri/0/i915_error_state. From my perspective, the
last contains the most interesting information (the batchbuffer executing
at the time of a gpu hang). If there is nothing in any of those, echo t >
/proc/sysrq-trigger and look for the stacktraces in dmesg.