corrupt environment?

[Emanuel Borsboom <emanuel@satyam.net.in>]

I'm running into a strange problem that I can't figure out, shown by the
following example:

(define get-value '*)
(let (...)
  ...
  (define value 42)
  (set! get-value (lambda () value))
  ...
  (write (eq? value (get-value))) (newline)	;prints #t
  (define foo 'bar)				
  (write (eq? value (get-value))) (newline)	;prints #f
  ...
)

This is in the context of a much larger (~3000 lines) program that uses
guile-gtk.

Any idea what could cause this?

I'm using a Debian 2.1 system with guile1.3 (package version 1:1.3-12)
and the latest gnome debs from ftp.gnome.org for the gtk stuff.