GHC 6.5 (Visual Haskell) bug with wxHaskell

I installed the alpha version of Visual Haskell and wanted to try to
add wxHaskell to the package list. I compiled wxHaskell from source,
using the ghc, ghc-pkg and Haddock from the Visual Haskell
distribution. The wx and wxcore packages are visible when I use
ghc-pkg list (and they're visible in add references in Visual Studio),
but whenever I try to use them (either by adding them as references in
VS or trying to compile an example using ghc-6.5 under CygWin, I get
the following error:

$ ghc -package wx helloworld HelloWorld.hs
<no location info>:<no location info>:
    ghc.exe: panic! (the 'impossible' happened, GHC version 6.5):
             unknown exception

Is this one of those "hidden bugs" due to the bundled version being a
prerelease, or am I missing something obvious?

-- 
Greetings,
Piotr Wilkin
pwl@xxxxxx