More information that may help you with the analysis. If an application is not full-screen, a trace of it remains on the screen when it's closed; if an application that is dragged around the screen, it leaves traces as in the photo attached here:
** Attachment added: "Screenshot at 2011-09-30 07:39:55.png" https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/863006/+attachment/2484987/+files/Screenshot%20at%202011-09-30%2007%3A39%3A55.png -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/863006 Title: Display problems after updates To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/863006/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs