I have found my first bug in the final code of Windows Vista. A few weeks ago after my hard drive was getting low on space I ran disk cleanup to try to delete some unneeded files. Since I needed a lot of space fast I also checked the option to clear my hibernation file. It turns out that was a big mistake.

After clearing my hibernation file my laptops ability to hibernate was destroyed. It was so badly damaged that I could not get to the control panel hibernation settings to turn it back on. Thanks Disk Cleanup!

The fix is actually very easy to do.. Since the control panel settings were gone, I simply used the the command prompt to turn it back on. If you have a similar problem, run the follow command at an administrative level command prompt to turn hibernation back on:

Powercfg /hibernate on

After a reboot the ability to hibernate is restored.

Update: Microsoft now has a KB article on the bug as well.