A brand new Dell Optiplex, XPSP2, member of a domain, simply refuses to stay awake. I have set the power profile for every user to "always on" and set the profile for the .default user in the registry to "4". Nevertheless, it always suspends after a few idle hours. This is a real issue as it is used for remote access and backups :(
I can only guess that it is picking up the power profile from the domain, yet every search I've run to find out how to control power profiles on the stations via domain policy says it can't be done. Two other stations, nearly identical (same model and OS) do not exhibit this symptom (the other 30 stations on the network are shut down at night).