I think this is bug has something to do with the gnome-screensaver package. I have exactly the same problem here. I first installed the gnome-screensaver package mentioned above, but this didn't solve the problem. So I removed the package and now i can switch between users as many times as I want and it works perfectly.
-- [RS480] 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