[Haskell-cafe] "could not create compact unwind"

[Richard O'Keefe]

I just did
	cabal install cabal-install
on a Mac running Mac OS 10.6.8 and got the eventual response
[44 of 44] Compiling Main             ( Main.hs, dist/build/cabal/cabal-tmp/Main.o )
Linking dist/build/cabal/cabal ...
ld: warning: could not create compact unwind for .LFB3: non-standard register 5 being saved in prolog
Installing executable(s) in /home/cshome/o/ok/.cabal/bin

I also had this problem today:
m% cabal install quickcheck   
Resolving dependencies...
cabal: dependencies conflict: ghc-6.12.3 requires pretty ==1.0.1.2 however
pretty-1.0.1.2 was excluded because ghc-6.12.3 requires pretty ==1.0.1.1

What's the procedure for wiping everything out and starting again?