Certainly windows vista is pain for many, that includes me as well. But somehow i have to live with it because that is the OEM version i got with my laptop. Windows XP was way better than this drag. Lol.. lets not condemn Vista anymore and let me show you how can you enable hibernation which you disabled it and you dont know how 😛
1) Goto Start type Command prompt then right click on it to click “Run as Administrator”
2) After you click Continue on the User Account Control message you should be able to see black window i.e. Command Line
3) Now type the following as per requirement
To enable Hibernation >> powercfg -h on
To disable Hibernation >> powercfg -h off
That should work.