Sorry for posting again, I should have tried this first: this only happens with visual effects enabled, so it seems to be a Compiz issue. When disabling visual effects, everything works fine.
I found some bug reports which reported similar but mentioned that "the computer freezes". In my case, only the video output on the external screen freezes. Everything else works as usual. -- Video freezes at pass in a full-screen mode https://bugs.launchpad.net/bugs/379799 You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is a bug assignee. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
