[racket] Problems using Sandbox and Scribble

Hi.

I want to evaluate some scribble things (in a sandbox) and then
combine them with other scribble things I already have lying around.
But I'm running into a problem.

If I, for example, make a nicely formatted (racket) code block in a
sandbox, and then put it in a (para) outside of that sandbox, the
world explodes. Here is a minimal example:

#lang racket

(require racket/sandbox
         scribble/manual)

(define safe-eval
  (make-evaluator 'racket/base #:requires '(scribble/manual scribble/racket)))

(pretty-print (racket foo))  ; Gives one output
(pretty-print (safe-eval '(racket foo)))  ; Gives a slightly DIFFERENT output

(para (racket foo))  ; Finishes happily
(para (safe-eval '(racket foo)))  ; Error

; end

This is the error I get:

para: contract violation
  expected: pre-content?
  given: (cached-element (style "RktSym" (list 'tt-chars (css-addition
'(collects #"scribble" #"racket.css")) (tex-addition '(collects
#"scribble" #"racket.tex")))) "foo" (vector (style "RktSym" (list
'tt-chars (css-addition '(collects #"scribble" #"racket...
  in: an element of
      the rest argument of
      (->*
       ()
       (#:style (or/c style? string? symbol? #f))
       #:rest
       (listof pre-content?)
       paragraph?)
  contract from:
      <pkgs>/scribble-lib/scribble/base.rkt
  blaming: anonymous-module
   (assuming the contract is correct)
  at: <pkgs>/scribble-lib/scribble/base.rkt:337.2

What is going on? Why does the same piece of code have two different
results depending on where it's executing? And most importantly, is
there a way for me to get this to work the way I /want/?

- Lucas Paul