My problem is: the computer wants to start, the fans kick in, then a second later the system shuts down completely. I've searched through previous threads and can't find one that really applies to my problem. Any help would be greatly appreciated! Our desktop is an HP 533w (a gift from my brother in law). It worked okay for a while, although the PSU seemed to be faulty. Basically, the computer would randomly shut down, and then wouldn't start up. A couple of times my husband cleaned it with compressed air, and it worked okay for a while, then started with problems again. Eventually it stopped starting up altogether. I thought it might be the PSU so I replaced it with a larger one (it was a 200W, went for a 400W). No dice. I think it may be the motherboard. HOWEVER... when I was installing the new PSU I had to remove the cooling fan off the CPU and found a greasy gray substance on it. Could this mean that either the CPU or motherboard are done? Thank you for your help!