The "Sleep" function, is, by default, the same as Hybrid sleep. The power will always be on. The alternative, which means a short boot up on resuming use of he computer, is,of course, "hibernate".
But, anyway. Try this:
A) In the elevated command prompt, (Right click and run as Administrator)
type powercfg -h on and press Enter.
B) Now, if you wish, set your Power Plan settings to the recommended settings for Hibernate. But I think the system is looking for the "hyberfil.sys" file in the root, which you may have accidentally have deleted. The command above will restore it after a reboot.
Fwiw. The Windows 7 Beta release has expired. I do not know all the symptoms this may produce, but it will fold on you with limited functions. This could be one of them, although I doubt that.