I have a new Lenovo Z360 laptop. About 1 in 5 times, instead of suspending when I close the laptop lid, the screen goes blank and the machine freezes and stays on, with the fan running. I have to hard-boot at that point, which sucks. I haven't been able to narrow down the scenario, exactly. This laptop doesn't have the NVidia card, just the Intel video. I've turned off desktop effects which didn't help. It has happened while plugged in and not plugged in.
Update: Upgraded to Ubuntu 11.10 and this issue still happens.
Debug notes (per https://wiki.ubuntu.com/DebuggingKernelSuspendHibernateResume):
There are no flashing caps lock lights or similar.
Setting the boot param
no_console_suspend and then switching to VT1 and running the commands
setfont /usr/share/consolefonts/Uni1-VGA8.psf.gz and
sudo pm-suspend will trigger suspend with this issue, but there is no text output beyond the last command.
The computer also freezes on shutdown (without actually shutting down) right after printing Power Down on the console.
[10123.4321] Power Down.