In reference to http://www.nabble.com/6.10.3-prerelease-td23346957.html I also run Mac OSX 10.4.11 (there are some left) and I experience the same problem but with the full release of 6.10.3 from source. I've read the discussion and the trac ticket at http:// hackage.haskell.org/trac/ghc/ticket/3243, but I have no idea how to actually get and apply the patch. Sorry if I'm being incredibly thick, (or even just a bit thick) but I have barely used C or darcs (though I do have darcs installed). Any advice on how to fix this is much appreciated - originally I just wanted to upgrade Cabal but when it didn't work I tried to upgrade GHC, and now I seem to be digging a big hole! Iain