Suspend not working after upgrade to 14.04

[Adam Funk]

I upgraded my laptop to 14.04 & now suspend isn't working --- I log
out & close the lid, & find it's run out of power later.  Testing with
"sudo pm-suspend" (while logged in), I find that it starts to suspend,
then comes back up, leaving the following in the syslog:

Jun 22 15:35:39 gonzo kernel: [ 1503.932446] PM: Syncing filesystems ... done.
Jun 22 15:35:39 gonzo kernel: [ 1503.995316] PM: Preparing system for mem sleep
Jun 22 15:35:44 gonzo kernel: [ 1504.819644] PM: Entering mem sleep
Jun 22 15:35:44 gonzo kernel: [ 1506.898757] PM: Device 0000:01:00.0 failed to suspend async: error -16
Jun 22 15:35:44 gonzo kernel: [ 1506.898814] PM: Some devices failed to suspend, or early wake event detected
Jun 22 15:35:44 gonzo kernel: [ 1509.459217] PM: resume of devices complete after 2560.147 msecs
Jun 22 15:35:44 gonzo kernel: [ 1509.471411] PM: Finishing wakeup.


The output of "sudo lspci" includes the following line:

01:00.0 VGA compatible controller: NVIDIA Corporation GT218M [GeForce 310M] (rev a2)

Is that the same as the "0000:01:00.0" in the syslog error?  Any
suggestions for debugging & fixing this?  (No hardware has been
changed, & suspend worked fine in 13.10.  I've tried "sudo aptitude
reinstall pm-utils" and "sudo dpkg-reconfigure pm-utils".)

Thanks,
Adam