I have the same machine as Francisco, the submitter. I have tested the upstream kernel 2.6.34 and verified that the bug is still present. Then I applied this patch to the upstream kernel: http://lists.freedesktop.org/archives/intel-gfx/2010-June/007232.html
and verified that it fixes the bug. I recommend that the Ubuntu 10.04 LTS kernel adopt this patch.
I have the same machine as Francisco, the submitter. I have tested the upstream kernel 2.6.34 and verified that the bug is still present. Then I applied this patch to the upstream kernel: lists.freedeskt op.org/ archives/ intel-gfx/ 2010-June/ 007232. html
http://
and verified that it fixes the bug. I recommend that the Ubuntu 10.04 LTS kernel adopt this patch.