Didn't ghc 4.08-1 just come out in the last couple of months or so? Maybe there have been some bug fixes that deal with this. Of course, maybe not.
I think Simon Marlow is very well placed to be able to comment on whether GHC has the problems Claus reported and whether they're just minor bugs or (and this is how I read his email) fundamental to the way GHC is implemented. (See the hall of fame in the GHC web pages for reasons to believe this but don't believe the photo on his home page - he doesn't look so glaikit in person.) -- Alastair Reid ps ghc 4.08-1 has a major bug in the finalizers which makes it unusable for people who need finalizers, the foreign function interface, etc. (There is a fix in the CVS repository but you have to build GHC yourself from source to be able to use it.)