This may not be your problem but inhale had several clients that have had similar issues. Their laptops would randomly go to sleep or hibernate (which ever they had the kid close action set to). Turned out to be that it was the same user it happened to all the time and she had a magnetic bracelet on and whenever ever the magnetic part of the bracelet would cross over the magnetic old switch in the palm rest it would kick off the old close action and sleep or hibernate. Something to be aware of anyway. Otherwise I agree disable hibernation. Many computers APCI functions just don't work well. Also this is a laptop I presume? Have you checked the event logs to see what's in there? Many users know the setup, security, and application logs but if you expand the Windows tree and dig in you can look for the hardware and or functions of APCI and see what's in those specific logs it may shed some light.
