Dual boot problems?

I find that when I install W2K Professional on a second partition it causes NT 4.0 of the dual boot to give me the blue screen on shut down. I can correct the problem by reinstalling service pack 5.

Now a new problem is created on startup. On the screen for selection of operating sytem When I select W2K the machine restarts itself and does this all the time I select W2K. Why?