>  Hmmm.  Yes, that does seem to eliminate the possibility of this being a
>  transport issue, which only makes it more puzzling.  You aren't running out
>  of disk space, are you? (To ask the obvious...)

It may be worthwhile to do the crc check on the repos you're pulling
from, both local (NEW) and remote ( http://darcs.haskell.org/ghc )

I think it's:
 for i in _darcs/patches/*.gz; do zcat $i > /dev/null; done 2> crc-errors
 grep crc crc-errors | sed -e 's/gzip: //' -e 's/gz.*/gz/' > bad-patches