The Win32 installation instructions say that one should execute "mount -f C: /", but having done that in response to this error it does not fix the problem and it stops bash from starting up correctly (Cygwin is installed in c:\cygwin and GHC in c:\ghc\ghc-4.08.2). (Why am I supposed to do this mount?)
It helps because it means that Cygwin's UNIX-style paths (starting from /) are also valid Windows paths. However, as you've observed, when installing Cygwin in its default location, it stops other things working, and I've now retracted that piece of advice. Unfortunately, not mounting C: at / messes up other things (though more so when building GHC than when merely using it). Mounting C: at / shouldn't stop bash starting up, though...
Has anyone got a solution?
There should be some hardwired paths in the driver (/ghc/ghc-4.08.2/bin/ghc-4.08.2) and possibly other scripts that start with /cygdrive/c; changing these to C:/ should make things work. If the paths are being generated somewhere, then running them through cygpath -w will convert them into Windows format. I'm working on getting this cleared up in the head, for the upcoming GHC 5.0 release...hopefully Cygwin 1.2 will be out soon, and then things will settle down somewhat. -- http://sc3d.org/rrt/ | computation, n. automated pedantry