I mentioned there might be a problem with filenames containing spaces.  I 
just tried a few things and managed to reproduce some strange behaviour.

'darcs' is darcs 1.0.9
'darcs2' is darcs-unstable pulled yesterday

$ mkdir foo
$ cd foo
$ darcs init
$ touch 'A B'
$ darcs add 'A B'
$ darcs rec -a
What is the patch name? fo
Do you want to add a long comment? [yn]
$ ls
A B  _darcs/
$ darcs check
Applying patch 1 of 1... done.
The repository is consistent!
$ ~/darcs/darcs-unstable/darcs check
The repository is consistent!
$ cd ..
$ ~/darcs/darcs-unstable/darcs convert foo foo2
Finished converting.
$ cd foo2
$ ls
A B  _darcs/
$ ~/darcs/darcs-unstable/darcs check
Looks like we have a difference...
Difference:  rmfile ./A

Inconsistent repository!
zsh: 20274 exit 1     ~/darcs/darcs-unstable/darcs check

This behaviour is *not* fixed by recompiling with --disable-bytestring, 
incedentally.

Also, darcs2 fails to check the GHC darcs2 repository, giving this error:

rmfile ./WindowsInstaller/Glasgow\92\32\92\Haskell\92\32\92\Compiler.ism

Inconsistent repository!

Cheers,
	Simon