Okay I updated to the latest Beryl version (0.1.9999.1) yesterday and the problem is gone / everything works fine. just a few firefox crashes, but not more anything as critical as a systemwide frozen computer.
thanks for your comments (btw me is gnome user) -- Firefox freezes Ubuntu Suddenly - Reboot needed https://launchpad.net/bugs/83132 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
