My OS, XP Pro, was working badly. I launched the PRO cd setup from inside windows and it ran, when I came back later it had an error on the screen, black screen on the 'rebooting' portion that reported a disk error and requested to hit cntrl-alt-delete to retry. I do that and choose windows xp professional rather than XP Professional Setup, (which is a choice every time I boot up now), an unpleasant aftereffect from the failed part of the reinstall/reboot. I assume the failure is because I have an SSD hard drive in the PC, but who knows? What I want is for the 'setup' choice to go away when rebooting and for the registry to let me 'use' it freely now, to install new software (namely Quicktime, although I have tried three other programs today too and can't install adobe reader updates either as they fail too). So I believe the registry is 'write-protected' at the moment, but since the OS is working so nicely and I am happy with that outcome I would like instructions on how, through booting to a linux CD or my Bart's PE CD or recovery console, to unlock the registry so that it stops preventing me from installing new software.