Windows 7 Beta would go into hibernation mode if selected but after installing the release candidate, nothing I have tried will allow my Toshiba notebook to automatically hibernate. I have to do it manually. I also am wondering why sleep mode is on the menu but it is grayed out leaving only hibernation, shutdown or restart.

Check your power plan and BIOS settings. Installing buttons application for your model might help resolve this issue. Regards, i.shaikh