I just installed the generic 7.0.2 binary on Ubuntu on both 32 bit and 64 bit machines. Then I rm'd .ghc and .cabal then fetched the current haskell platform. Built and installed. After cabal installing all of the dependencies cabal said were required for yesod, I run yesod.. the script creates the project. When executing runhaskell devel-server.hs I get this message GHCi runtime linker: fatal error: I found a duplicate definition for symbol ghczm7zi0zi2_AsmCodeGen_zdfMonadCmmOptM2_closure whilst processing object file /usr/local/lib/ghc-7.0.2/ghc-7.0.2/libHSghc-7.0.2.a This could be caused by: * Loading two different object files which export the same symbol * Specifying the same object file twice on the GHCi command line * An incorrect `package.conf' entry, causing some object to be loaded twice. GHCi cannot safely continue in this situation. Exiting now. Sorry. it's the same on both 32 and 64 bit. Any ideas? I am going to try to build 7.0.2 from source to see if that fixes it.