mod_ruby / Apache 2 - Output stops in middle of page

Hi,

Our custom error page displays fine for bad URLs underneath /inns/:
http://special.characterinns.org/inns/abc

However, if someone goes to a top-level URL, the server never finishes 
outputting the page:
http://special.characterinns.org/abc

This seems quite strange. Our expert Ruby contact suggested that I 
should check here based on the chance that it could be a mod_ruby issue. 
This server is the first we've tried with Apache 2.0.54 (on Ubuntu 
Breezy). We've been running the same site on Apache 1.3 on Debian for 
some time without this problem occuring.

Thank you,
Ben