Unable to stop or start any services

Hi,
I have a windows 2000 server. For some reason I’m unable to stop or start any services. When I do try the service screen freezes. I have to end task. Rebooting does not help. I even tried msconfig to disable services and this also freezes. There was one service I had to start and I did this through making a registry change. And rebooting. Is there a reason the computer is in this state and how this could be fixed? Any help would be appreicated. Thank You