HP compaq nx5000 laptop freezes with 12.04, which kernel parameter could fix it?
Solution 1:
look in /etc/default/grub
change the line
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=off"
and now just update grub with sudo update-grub.
Source.