Are you using compiz or beryl when having this issue? If I've understood well your issue, this bug looks similar to Bug #82999 (compiz).
Is it the same problem? -- [feisty] No screen updates when using desktop-effects https://launchpad.net/bugs/77442 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
