I've seen similar on-screen garbage, off and on, through dapper and edgy beta 1. You can probably work around it by switching to another console, and then back to X: ctrl-alt-f1, then ctrl-alt-f7.
-- After hibernate, monitor shows strange-colored lines https://launchpad.net/bugs/23090 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
