I tested your site in both FF and IE8
The image in the first article, Fishful Thinker pops up the image just fine in both browsers.
Also the Listen Live link.
So Im sorry but I don't see the problem on the site..
When did you install this mbox version?
note, your joomla version is old, unless you forgot 1 in front of 7
at least we would advise you to upgrade to 1.5.17