Comment 31 for bug 750437

I did not often shutdown my Ubuntu
Do you have try:
sudo /usr/sbin/update-r.d -f atieventsd remove
I thinh it will kill all ATI events, and diasable them when you start.
I tried add to /etc/default/grup
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force"
I think it can be ok for you.
May all being be well , happy and peaceful