I have a Dell Lattitude C600 with an ATI Mobility card, also. Killing acpid worked, but that obviously isn't ideal.
The only debugging I have done is that Xorg listens to acpid on a socket, and exits when it gets either the 'video' or 'button/lid' event. -- Xorg exits when it receives an ACPI button/lid event https://launchpad.net/bugs/61746 -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
