http://bugs.winehq.org/show_bug.cgi?id=19873
--- Comment #19 from Michael Abbott michael@araneidae.co.uk 2009-09-04 06:43:32 --- (In reply to comment #4)
Lots of Wine parts relay on being able to access (/) regardless via what drive - z: or anything else. If you removing z: mapping, you creating unsupported configuration.
http://wiki.winehq.org/FAQ section 10.1.5:
Consider removing the default Wine Z: drive, which maps to the unix root directory. This is only a weak defense, but it might help against some attacks.