I just tried with the nodri line (checked it and DRI was effectively disabled) using 2.6.33-2 and same weird behaviour happened, at the xscreensaver I wasn't able to authenticate after the pm-hibernate and when I went to a tty it was not able to spawn a login and got some error about an assertion not ok, so I believe that again this points to the memory corruption thing. Again, KMS seems to be the only one to blame here. Regards.