In addition to deploying my ejb.jar files, I also put them under the WEB-INF/lib directory of my .war . I then import them in my JSPs.
That way they are in the classpath for your war, and accessable to my JSPs.
when you put your ejb files under the jboss/lib/ext directory, you were adding them to the general classpath (I believe). This is why things started working. While this may work, it may not be the best idea... It's a much better idea to just make sure your ejb classes are in your war.