I had the same bug. After logging more than one user and logout one of them I got the black screen.
I've updated nvidia drivers to 173.14.27 and the bug has gone. Adding repo with the latest drivers for nvidia cards sudo add-apt-repository ppa:ubuntu-x-swat/x-updates sudo apt-get update sudo apt-get upgrade Now I can switch between users and logging out at any moment. $ nvidia-settings -q NvidiaDriverVersion Attribute 'NvidiaDriverVersion' (connie-desktop:0.0): 173.14.27 $ uname -a Linux connie-desktop 2.6.32-25-generic #43-Ubuntu SMP Wed Sep 1 09:46:39 UTC 2010 i686 GNU/Linux -- black screen after a few user switches https://bugs.launchpad.net/bugs/546578 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
