ntoskernal.exe error

when trying a new installation of nt4 or nt4 svr on a test machine(p 300 64mb 10 gb hd) it gets halfway through the load then come up with a blue screen and "ntoskernal.exe error" what can i do to make this os load.
i have tried all installation methods cd/floppys and get the same problem.
this machine did have win 2000 prof on it but now if we try to load this back on ,it to comes up with "ntoskernal.exe error"
is it a hardware problem or is there a way i can bypass this error.
all help would be greatly appreciated