Comment 55 for bug 750437

Problem still occures on Toshiba A300 with ATI Radeon 3470. (Ubuntu 12.04.2, gnome-shell).

Almost every time I was informed that watchdog detected hard lockup on cpu. (No log file to post at the moment)

I've tried adding "nomodeset" to GRUB_CMDLINE_LINUX_DEFAULT, but with no luck.

Also tried this solution: http://mylinuxexplore.blogspot.com/2011/11/solved-ubuntu-doesnt-shutdown-properly.html, which didn't solve it either.

No issue with open source drivers.

WORKAROUND:

For the last month I've been able to shutdown safely, killing Xorg first.

sudo killall Xorg && sudo shutdown -P now