Images only after edit

Here is a wierd one.

I have two images on a wikipage in a table as follows.

|| width=100%
|| ||
|| ||
|| [+++The Edu-Coop Wiki+++] ||
|| ||
|| Attach:chicken.jpg ||
|| ||
|| [[http://www.pmwiki.org Attach:pm-m.jpg]] ||
|| ||
|| ||

When I browse to that page (Main.WelcomePage) the images don't apear 
becasue the substitution was not made.  The page source says someting 
like "<IMG SRC=Attach:chicken.jpg> where it should have had a path 
substituted in.

Here is the weird part.  If I bring up the edit screen, edit the page 
and submit the edit form or simply submit the form without making any 
changes, the images apear.

I can then see the images on al subsequent visits to that page.  

I did the local cache flushing, etc and am now fairly well convinced 
that the problem is in the script someplace.

I am in the middle of a whole list of diagnostic tests, but nothing yet.

Has anyone experienced anything like this?

Ross