Check that at least one drive is defined on startup

[Mike Hearn]

On Mon, 2004-05-24 at 12:19 -0700, Alexandre Julliard wrote:
> That's a different problem. The Drives key is only used to override
> the autodetected drive types, so it shouldn't matter if it's
> missing. The drive symlinks themselves are obviously more important,

Ah, sorry, I hadn't kept up with the file system changes. I'd forgotten
the registry keys aren't needed any more.

I suppose the problem was that the symlinks weren't being seen or
something. I'll remove the keys and try again.