ghc.exe: panic! (the 'impossible' happened)

Hi,

I was advised to report it here ... and
  maybe somebody who knows ghc better can
  reproduce it or knows what is the problem.

I uninstalled all ghc, gtk, and gtk2hs
  packages then installed ghc 6.8.3 and
  then gtk2hs 0.9.13 on Windows XP 32bit.
This should not be because of some stalled
  files from previous ghc as it was suggested
  to me. And I was told there is nothing
  strange in gtk2hs 0.9.13 to cause this.
A version of gtk2hs 0.9.12.1 I compiled
  myself works with ghc 6.8.3. I did not
  try to compile 0.9.13.
Any ideas?

Peter.

status:0 peter <at> dwarf [764] /c/tools/Gtk2Hs/demos/hello
% ls
Makefile  World.hs
status:0 peter <at> dwarf [765] /c/tools/Gtk2Hs/demos/hello
% ghcii.sh World.hs
GHCi, version 6.8.3: http://www.haskell.org/ghc/  :? for help
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( World.hs, interpreted )
Ok, modules loaded: Main.
*Main> main