Comment 5 for bug 426319

Dimas, we know that there are problems in Jaunty, and at this point we are only interested in identifying problems that are not fixed in Karmic. You may upgrade to Karmic, reinstall Karmic from a recent CD image or test a LiveCD. If you want to test a LiveCD, Karmic beta should be available at http://cdimage.ubuntu.com/releases/karmic/ tomorrow. If you find a problem which is not exactly the same as this one, please file it as a new bug with the ubuntu-bug command.

Giovanni, I would like you to test some updates which are not yet in Karmic. The x-updates PPA [1] contains an updated mesa and an updated -ati driver. They may make it into Karmic, especially if it fixes bugs like this one. Could you first test with those?
If it isn't fixed by those, there is the even more bleeding edge xorg-edgers PPA [2] which holds the latest development version of mesa. If it is fixed there, we may try and find the patch that fixes this problem and include in Karmic. If it still present with xorg-edgers, we can report it upstream, since this is something they will want to fix there. In this case it will take longer to fix, but if the fix is small enough it may be possible to include it as an update to Karmic.

[1]: https://launchpad.net/~ubuntu-x-swat/+archive/x-updates/
[2]: https://launchpad.net/~xorg-edgers/+archive/ppa