I downloaded and extracted the *nix version of tkdiff under my Cygwin
home directory. When I attempt to run it I get an error dialog
reading:

+----------------------------------------------------------------------------------------------------------------------------------------------------+
| TkDiff: Error

     |
+----------------------------------------------------------------------------------------------------------------------------------------------------+
|    diff failed:

       |
|       1[main] diff 136 C:\cygwin\bin\diff.exe: *** fatal error -
could not load user32, Win32 error 487          |
+----------------------------------------------------------------------------------------------------------------------------------------------------+

Googling for this error indicated that I needed to run rebaseall. As I
understand it rebaseall needs to be run from an ash shell started from
Windows with all Cygwin processes terminated so that the DLL is not in
use. I rebooted and attempted to start ash from a cmd terminal window.
Unfortunately ash is generating the same error as diff did when run
from tkdiff. Help?

C:\cygwin\bin>.\ash.exe
      1 [main] ash 4500 C:\cygwin\bin\ash.exe: *** fatal error - could
not load user32, Win32 error 487