you have whats called "the service pack 2 reboot cycle" spk2 is conflicting with something in your sys. did you say tried a repair install off the ms cd (which is essentially reloading a new os over the current os without losing data). also i dont know how computer savy you are but you could try these
ms article
repair install
prepare for spk2
but if you have access to another hard drive i would back everything up first then try or at that point just do the format and reload of os. also what cpu are you running if it is a intel presscott cpu there may be extra steps to get your pc to accept spk2. ****disclaimer advice is given free of charge with no liabilty to me if you want to try the above you do so at your own risk****
