This has plagued me before on another notebook computer. I never figured out the problem on that machine so I resorted to just shutting down every time I moved from home to office because hibernation never worked for me.
I started getting this “System Hibernation Failed” warning again a few days ago on my current notebook.
System Hibernation Failed
The device driver for the ‘Standard 101/102-Key or Microsoft Natural PS/2 Keyboard’ device is preventing the machine from entering hibernation. Please close all applications and try again. If the problem persists, you may need to update this driver.
This time as I searched for the fix I found it. The answer to my problem I found on a message board and the problem was related to Adobe Type Manager. I uninstalled Adobe Type Manager and my notebook is once again hibernation when told too. Haven’t found the fix for using ATM and hibernating at the same time–but I can do without ATM–so it’s gone.