Have you tried the fglrx drivers. Please refer to https://help.ubuntu.com/community/BinaryDriverHowto/ATI to set up ati card for composite. See if you are able to reproduce this issue with the fglrx drivers (they are non-free) it also says in that wiki that the ati drivers dont support composite.
-- Often extremely slow at drawing things https://launchpad.net/bugs/76063 -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
