[plt-scheme] gui-exe problem

A scheme gui-exe used to work (plt 205, linux and windows), but
doesn't now (plt 206).

Here's a simplified version, arf.ss

(module arf mzscheme
  (require (lib "class.ss"))
  (require (lib "mred.ss" "mred"))
  (define frame (make-object frame% "Arf" #f 20 10))
  (send frame show #t)
)


It compiles.

[stanonik at duckfeet grades]$ mzc --gui-exe arf arf.ss
MzScheme compiler (mzc) version 206, Copyright (c) 2004 PLT Scheme, Inc.
 [output to "arf"]

But fails to run.

[stanonik at duckfeet grades]$ ./arf
simplify-path: expects argument of type <string>; given #f

Any suggestions?

Thanks,

Ron
stanonik at cogsci.ucsd.edu