I had the same problem with 12.04 LTS, x86_64, 3.2.0-27-generic, fully updated. It affected both Suspend and Hibernate, and Ctrl+Alt+Fs didn't work, so I had to switch off the machine. Then I realised that I had installed nvidia-current but not nvidia-current-updates, via the Additional Drivers app. Installing the latter solved the issue.
I had the same problem with 12.04 LTS, x86_64, 3.2.0-27-generic, fully updated. It affected both Suspend and Hibernate, and Ctrl+Alt+Fs didn't work, so I had to switch off the machine. Then I realised that I had installed nvidia-current but not nvidia- current- updates, via the Additional Drivers app. Installing the latter solved the issue.