I have a fresh install of Ubuntu 12.04 Precise 64-bit on a custom-built desktop PC. Sometimes (with no discernible pattern), it hard freezes after displaying the login screen when waking up after being suspended.
Here's what I'm seeing in the tail of pm-suspend.log:
Note how it just cuts off halfway through the word "success."
/etc/pm/sleep.d/10_unattended-upgrades-hibernate resume suspend: su
To be explicit, by "hard freeze," I mean I can't switch to another virtual terminal or restart the X session. My only choice is to use the hardware power or reset button.