Java EE (Java Enterprise Edition) General Discussion

I have a web application (servlet/jsp running under tomcat) which we've put on-line for a limited number of users for testing purposes. I'm now facing the following problem:

We use quite a few small gif files (about 1K) on every page (almost always the same gif files on every page) and quite frequently the user gets broken links to some of these gif files, however when they right-click on the broken link and select Show Image, the image appears. Also if they do a refresh of the page the image typically appears without a problem. I don't see any errors in the tomcat loggings. Any ideas what could be causing this? It is quite annoying for the end-users. Could it have something to do with the network connection?

Any help would be greatly appreciated!
Thanks,
Thomas.