I was able to reproduce these odd behaviors with Xubuntu 12.04 x64. Therefor it is probably not something Gnome specific as it happens with Xcfe as well.
I have not installed Virtual Box on this system yet. So that rules out all VM involvement. I did a bit of research. These rss-glx screen savers seem to come from Terence Welsh / Really Slick. I have contacted him directly, referencing this support thread. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/600603 Title: Skyrocket screen saver failing to start, screen dims, then pops back to 100% normal brightness To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/rss-glx/+bug/600603/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
