Comment 44 for bug 564181

A few other ideas to try out:

There have been some updates to -ati recently, and since you indicate this to be a regression that occurred in the last day, this would be the first thing I would suggest looking at. None of the ubuntu changes look like they could cause this kind of a bug, but who knows. It would be helpful if you could downgrade and test the following versions:

  * -ati: 1:6.13.0-1ubuntu1 - this will rule out two (innocuous?) changes in the last couple days
  * -ati: 1:6.12.192-2ubuntu2 or earlier - this will rule out upstream changes we brought in about a week ago
  * -mesa: 7.7.1-1ubuntu1 - this will rule out a change in the last couple days which I think is innocuous but who knows
  * xorg-server: 2:1.7.6-2ubuntu3 - this will rule out several patches recently added to xserver which were taken from upstream that look safe but may have changed something unexpectedly.

I haven't looked at what has changed in the kernel recently, but you probably have the -19 or -20 kernel. If you find you cannot reproduce it after booting into an earlier kernel that could point to a regression in the kernel.

Beyond that, look in your /var/log/dpkg.log file to see what got updated and go through downgrading them until you find a good suspect.