a bit more information.....
I also have to remove one of my jar files from the jboss/server/default/lib folder in order to make the .war application work fine. So there is something about that jar file that is causing the problem. I made sure that the offending class's package is not in the other jar file.
alas, I found the problem... and it had nothing to do with class loading. It had to do with my stupidity and the placement of certain classes in the wrong packages.