Cannot start Webrick under Aquamacs

I am running Aquamacs 0.9.9d on OSX Tiger on an Intel Mac. Got ecb,
rails.el mmm-mode, etc working great. But when I start Webrick (from
the Rails menu) it immediately stops. I can get into shell mode and
start Webrick from there. Everything I have running under Emacs on
Debian Sarge is working except for Webrick. Any ideas/pointers?
Thanks,

-bakki