Why W2k Pro Restarts instead of Shutdown

I have multiboot system with 98se,w2k pro,w2k srv,winxp. all of the os’s shutdown properly but w2k pro doesn’t. it restarts the system instead of power off. I have installed all the os’s on the primary partition C:. I have set the common permanent swap file between all os’s. That is also on the C:. When I repair w2k installation it solves the problem but, then winxp refuses to boot. when I repair winxp, the same problem rises again. I was running all this os’s healthy since long time. this problem ocuured suddenly.

please tell me how to get out of this problem.

Thank You…..