Ntoskrnl.exe is missing or corrupted

Hello,

When starting up my computer,it pops up,

Windows could not start because ntoskrnl.exe is missing or corrupt:

i tried the recovery console in my xp cd,
my cd-rom is in drive e: and windows install is in drive c:
so,
i try this code:
expand e:\i386\ntoskrnl.ex_ c:\windows\system32
but it is error,....The system cannot find the file or directory specified..

how can i troubleshoot this one??

HELP PLEASE..........