http://bugs.winehq.org/show_bug.cgi?id=30647
--- Comment #1 from beryllium@shaddybaddah.name 2012-05-11 09:24:56 CDT --- "I am unable to point my WINEPREFIX at a path that is off an ext2 partition, or more specifically, a vboxsf mount."
that should be "on a vboxsf mount".