The log indicates that your system didn't have a driver for synaptics, and that's where it failed. Configuration files were almost identical. The reason why you didn't have synaptics anymore is a mystery to me, but since I haven't seen similar issues open this is most likely fixed by now.
If you can reproduce it with a newer version, feel free to reopen. ** Changed in: xorg (Ubuntu) Status: Needs Info => Rejected -- ubuntu hoary to breezy fails to restart X https://launchpad.net/bugs/22528 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs