There is an incompatibility between the Windows 2000 Imagehlp.dll and the Windows NT 4.0 debugging tools.
To use the kernel-mode debug tools, I386kd.exe or Alphakd.exe, remove the Imagehlp.dll from the know DLL registry entry. This causes the tools to use their own version-specific copy of Imagehlp.dll.
Use Regedt32 to navigate to:
Select the Imagehlp value name in the right hand pane and delete it.
Double-click the ExcludeFromKnownDlls value name in the right hand pane and click in the Mult-String Editor Data to deselect any entries. Type imagehlp.dll on the first available blank line and press OK.
You must restart your Windows 2000 computer.