I have an ati radeon X1300/x1550 card in my Fujitsu Siemens desk top. the upgrade went OK but i had 2 problems.
Sudo was not working due to a host name issue which i sorted using the forum.
The second is proving more complex but it seems to a an issue with the ATI driver.
using this driver you can't logout or reboot using the GUI.
remove the proprietary driver and you can logout reboot shutdown from the GUI no problem.

I am using KDM but i have both KDE and Gnome installed the problem effects either desktop

The only way i have found so far to shut down is to open a terminal and do sudo halt now.

I have had a look at a few suggestions but so far these have not worked but these don't seem to point to the ATI driver.
Also i dont have any of the compiz stuff enabled.

Any other ideas on this would be appreciated