How to really turn off hibernation in Windows 7

You could also try to turn off Hybrid Sleep :

1. At the command prompt run as administrator, type powercfg.exe /hibernate off
2. Start menu > type Power options
3. In the left pane, open the link labeled Change when the computer sleeps and then open the link Change advanced power settings.
4. Under the Advanced Sleep options, expand the Sleep tree and turn off Hybrid Sleep.
5. Press OK.
6. Reboot.

I don't know if it matters but I always turn it off with the following command:

powercfg -h off

as opposed to:

powercfg /h off

I asked the question at and got the answer here: Microsoft Answers. So here is how you really find what is turning your hibernation back on again using clean boot.

1. Start msconfig.exe
2. On the general tab select "Selective startup" and uncheck "Load startup items".
3. On the services tab unselect all first. 
4. Runt the command "powercfg -h off" to turn off hibernation.
5. Reboot
6. If hibernation is still deactivated start msconfig.exe again and activate half of the services.
7. Repeat 5 and 6 until you find the service causing hibernation to be turned back on (don't forget to do step 4 if it is activated again).