[plt-scheme] Win32 + GNU Emacs + Quack: unable to evaluate regions

Hi,

I'd like to use GNU Emacs + Quack for Scheme development (DrScheme
gets confused by my heavily remapped keyboard).

I'm following the tutorial recommended on Quack's site:

http://www.cs.huji.ac.il/~osigor/emacs/pllab.html

BTW, whenever I evaluate a region with C-c C-r (scheme-send-region)
and  then switch to inferior scheme buffer to evaluate expressions,
the interpreter seems to wait for more input even when parentheses are
already balanced. Inferior scheme was responsive before. It seems
there is a problem regarding interprocess communications between Emacs
and MzScheme.

Here is my minimal .emacs:

(add-to-list 'load-path "~/emacs/lisp/site-lisp")
(require 'quack)

I'm starting MzScheme as inferior scheme, without any argument.

Software:
- Windows XP SP3
- GNU Emacs 22.3.1 (latest)
- Quack 0.36 (latest)
- PLT Scheme 4.2 (latest)

Any help?

Thanks in advance