Have a system that will only start up occasionally, runs great when it comes on. Owner just will not shut it down once he gets it going. According to owner system is overhauled, had a new motherboard and processor and case a year ago. Hard drive failed recently, that is where I came in. Replaced the hard drive and added a genuine Windows XP home. They had a "bootleged" windows xp before. Only 128 mb of memory and a 300w power supply. Could this be the power supply, memory or both. Bios has no beep codes. Suggestions?