stop error in win2k prof

On re boot after installing win 2k prof on a p4 with 256 mb ddr and 40 gb hd I get the following blue screen of death
stop:c000221/unknown hard error\systemroot\system32\ntd.dll

I have re-booted the pc several times. Do i need to reinstall the operating system or can the dll file be replaced any ideas would be much appreciated.

Kate cronin