We might still be looking at different bugs here. For me (on a system with Radeon 7200), the lockups were happening quite often (most sessions within a few minutes), but disabling DRI did fix the problem entirely. No lockups at all after disabling DRI (for a few months).
-- system freeze when using ati radeon 7000 with xorg "ati" driver https://launchpad.net/bugs/16873 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
