Why this hangs clisp?

Hi,

I am using SLIME + XEmacs + CLisp.
I wanted to try CL-FAD package (for file and directory manipulation) so
I wrote this simple test (using mpgtx utility to look at mp3 file
info):

(load "C:/Linux/cl-fad-0.3.2/load.lisp")
(in-package #:cl-fad-test)

(let ((files (list-directory "C:/Music")))
(dolist (item files)
(setq cmd-str (concatenate 'string "mpgtx -i " (namestring item)))
(with-open-stream (*output* (ext:run-shell-command cmd-str :output
:stream))
(loop for line = (read-line *output* nil)
when line do
(progn
(format t "~a~%" line))))))

It will display the outpout of first mpgtx -i some.mp3 and hang.
I have to go to the Task manager and kill lisp.exe process.
Any suggestions what's wrong here?

Andrei

.