To resolve this problem in Windows Vista, run the powercfg -h on command at an Administrative command prompt to enable the hibernate feature and the hybrid sleep feature.
The first thing you need to check if your computer supports one of the hibernation options. To do this, go to the start menu and type Command in the search box. In the results, right click and select “Run as Administrator”. When the command prompt opens up, type powercfg -a which shows you all of the available types of hibernation that your hardware supports.