Can others confirm that this lock up still occurs with the "ati" driver? Please attach your /var/log/Xorg.0.log.old file after rebooting when experiencing this problem.
I'm going to assume the lockups when running fglrx are all already fixed - if not, and you can confirm lockups when using fglrx >= 8.37.6, please file a new bug.
Can others confirm that this lock up still occurs with the "ati" driver? Please attach your /var/log/ Xorg.0. log.old file after rebooting when experiencing this problem.
I'm going to assume the lockups when running fglrx are all already fixed - if not, and you can confirm lockups when using fglrx >= 8.37.6, please file a new bug.