At a family get-together, I was recently asked by a war veteran who saw me tinkering with my hp pavilion laptop whether or not I knew "how to fix them things?" I asked what his problem was and he noted the last time he tried to boot his laptop it wouldn't start. His was also an hp pavilion. I told him to drop it off and I would see what I could do.
Upon initial investigation I found that the laptop would POST and the XP logo appeared as the OS began start-up, but then it suddenly would reboot...just as he indicated. So I decided to boot up Puppy Linux and see if I could access his hdd. I found I needed to boot with puppy pfix=ram (or something like that) since the Puppy startup script would hang when searching for the pup_save.sfs file. This was the first indication of a problem with the hdd. Once booted, I clicked the sda1 icon at the bottom left of the desktop and found (after futzing things up and a few reboots due to impatience) after about 120 seconds an error box indicates a problem with the drive and then after (no exaggeration) 20 minutes the ROX window finally opened and displayed the contents of the drive. After this initial wait, it took a mere 2 to 5 minutes for subsequent directories to open. It seemed as if the drive was spinning at only 10x or so.
Only 3 or 4 hours later (yes I was working on other stuff also) I had transferred the files that the owner cared to save to my external hd and started the reformatting and installation of my copy of XP. An hour after that I had XP installed and later at home I finished up with transferring his important data back. Success!