I had an empty device manager on my windows 2000 server system. None of the steps
above worked for me so here is how I got mine up and running again.
1. Disable Plug & Play in normal windows.
2. Boot into safemode without networking
3. Change the permissions as described many times above.
4. Change the plug & play back to automatic startup.
5. Push the start button on the plug & play service.
6. Go to your device manager and it should be full.