My main laptop died the other day, I’ve had enough. It didn’t die hardware wise, a single file in the Windows XP Pro install got damaged & that was it. The machine was dodo like. After some checks with the Recovery Console and various F8 options (like don’t reboot on a crash so that I can see the error!) I discovered that the software hive from the registry was damaged, there were a couple of MSDN/TechNet notes on how to recover from this, including using the Recovery console to remove the existing hives & replace them with some backups from the original install, you can see more here.