Images Not Displaying From Snapshot Or Cached Report

Hello,
This is my first post, and I'm hoping you all can help.

Using Reporting Services 2005, I have several reports that use embedded images.
All images render fine when the report execution is set to:
1) Always run this report with the most recent data
1a) Do not cache temporary copies of this report

However, when I change the execution to either a Cache or a Snapshot, the images and some charts render as red "X" placeholders. This is sometimes remedied when the user clicks the page refresh button, but not always.

Of course, I could just have all the concurrent users use the uncached report that hits the OLAP server, but that would be highly inefficient, and just plain slow.

Thanks for any help on this subject.

-michael