Vista - Windows Vista will not go into hibernation

Hello,
I am using Windows Vista Ultimate with all the available updates loaded.
When I try to place my computer in Hibernation mode, the computer acts like
it is powering down and then logs my computer off and takes me back to the
log in screen. I have tried several different methods to fix this issue.

1. I checked to make sure none of my hardware drivers where in beta or
conflict with Vista features.

2. I deleted the Hibernate.sys file, disabled hibernation in the command
prompt, restarted the computer, turned hibernate back on and hoped that when
in created the new hibernate.sys file that it would fix the issue.

3. I checked and made sure that I disabled the hybrid-sleep mode

4. I tried to run the System root command for hibernating as an
Administrator

5. I checked to make sure that the “Multimedia� Settings the Power Options
would allow the computer to Hibernate or Sleep

Nothing I have done so far seems to work. It was working just find a couple
of days ago and then all of the sudden just stopped working. I did not make
any hardware or software changes to the computer and not updates were
installed. Any ideas?