Do you hibernate?

It's a power off option in Windows.

You need to have Hibernate enabled and enough space to save your computer's RAM to the hard drive.

Hope this helps.

I find my drivers do not support the S3 sleep state in the BIOS ... and therefore have had to default to the s1 sleep state which uses more power .. hibernate in windows 7 is still flakey. You cannot hibernate with more than 4gb of ram with Windows XP 64bit.