The unit has no problem going into Sleep Mode at the designated time however, I cannot wake the computer up after it is Sleep Mode. It used to only happen when I was on batter power and it would fall asleep. Now it happens even when it's on AC power as well. A hard boot is required each time to get the system working again.
My guess is that sleep mode is locking up the registry upon restore. It could be a sign of a corruption in the OS (which you use a system restore disk and do a repair)... that will require all software to be reinstalled but will not lose any data. You can also try to set your power options in the control panel and turn off sleep mode... it is a fix for the symptom but doesn't fix the problems root.