Hi - new member and first post. Joined here looking for a resolution to the faulty 'sleep' function. I had the problem with the pc (Dimension E521) waking itself from sleep constantly rather than any problem in putting to/waking from sleep. Others have posted here advice on disabling the ability of certain devices to wake the pc - I followed all of that but the problem was, for me, only resolved when also I removed a USB printer (HP d155xi) from the sytem. I did this because the printer malfunctioned rather than in connection with this problem, but, for several days now, the sleep function seems to be working as intended. I have another USB printer connected still, so this solution may be of limited application but thought I would share anyway.