Hi everyone, I have an HP Pavillion 8390 that I loaded with XP. It is all stock including hard drive. It was running great when I tried to put a new hard drive in with a possibly corrupt WIN2k already on it. I was trying to fix a different computer and find a good hard drive by checking it on my computer first. Bad mistake. That didn't work, the little bar at the bottom for WIn2k would load then the computer would restart before the Window screen would start up. Well I tried to put my original hard drive back in with everything exactly as before, then I get the "no operating system found". Checked my BIOS and nothing found under the primary. No discs or anything in the other cd drives or floppy. I cleared the CMOS and still same result. I tried the hard drive on a different WIN2k machine and it found the hard drive in the BIOS but wouldn't start the XP. My computer was running the XP just great then I think that hard drive with WIN2k on it did something to my computer. My HP hard drive is Quantum and the other Win2k drive is a Seagate. The BIOS does see the Seagate, it just doesn't see the original HD.