The s key does not work

[Kai Großjohann]

This is weird, isn't it?  I just installed Cygwin and its X11 server
some days ago.  I verified using xev that the X server is seeing all
kinds of key events, but when I hit the s key, the X server isn't
seeing any event at all.

The s key works fine in Windows applications.  I've also got X-Deep/32
installed, where the s key works fine.  I can boot the box into
GNU/Linux natively, where the s key also works.

So the s key works everywhere except in the X server that comes with
Cygwin.

I don't know where to start looking.

Kai