No big deal, but I had XP SP2 set to hibernate after 5 hours. I had left the PC turned on for 6 hours, then went upstairs to where the PC is and saw that the monitor screen was blank (all fans still spinning in the case, etc), I rebooted and XP powered up as normal - no problems. I have also noticed that when I have manually tried to put the PC into hibernate, it just reboots. Perhaps I have not configured something in BIOS? Any thoughts? Thanks, David.
Go through Desktop Properties > Screensaver Tab; Power button.... Check if there is smthing wrong clicked over there...