Fix SERIOUS bug in winecfg

[Mike Hearn]

On Tue, 2005-10-25 at 01:33 +0000, James Hawkins wrote:
> Couldn't we check that Z points to / already before we swap the
> drives?  If Z already points to /, then we would drop the current
> letter we're adding; otherwise, wouldn't we have two drive letters
> mapping to /?  Besides that point, it looks good to me.

Yes, good point. Though I think this one missed the boat so we may as
well fix the underlying problem, which I guess Michael correctly
identified. I thought it was the unixfs as some of the debug output was
related to that, but there was quite a lot (cascading failures I guess).
The desktop shell folder still having references to Z: in the registry
sounds much more likely.