Just tried FF...and the image that is missing doesn't show up at all. So, with FF...either the image is there...or it's not.
With IE7...the image is there...or you'll see the red "x" denoting a missing image.
Update...
I made mention that it may be a problem with the index.template.php file associated with the Theme, but I think I may be mistaken.
Maybe all that has to be done is the uploading of the correct gif image to the images directory of that theme...or to rename the missing gif file from .gif to xx.gif.