Sounds like you have the GPU hanging. Take a look at https://wiki.ubuntu.com/X/Troubleshooting/Freeze for how to obtain a batchbuffer dump that is needed to troubleshoot issues like this.
** Tags added: 965gm freeze karmic -- X3100 intel graphic card + compiz = freeze https://bugs.launchpad.net/bugs/459230 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs