Comment 41 for bug 762203

rebuilt system to fresh install of natty and found with a combination of 'acpi=force' and also having rt2800pci blacklisted things worked for me, thought i would do more testing using the proposed kernel worked but i wanted to work out more what was happening with the system.

here are the workaround steps which worked for me;

1. edit "/etc/default/grub" change
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to
GRUB_CMDLINE_LINUX_DEFAULT="acpi=force"

2. Update grub
# update-grub

3. Blacklist rt2800pci
# echo "blacklist rt2800pci" | sudotee -a /etc/modprobe.d/blacklist.conf

restart machine and things worked, hopefully this helps others out.