Unexpected cured os

I had problem with win2k loaded on 915 original m/b where addon cards are modem & tv tuner giving yellow round for not able to give resources. so i loaded winxp still same thing. Even i keep only 1 card in pci slot. then i put both cards & left site after 2 to 4 days my colligue gone on site & found all working ok this makes confidance loss in troubleshooting. what would have happened so it gets sorted automatically.