Could the problem you are having have anything to do with this post? That error was happening because jasper-compiler.jar and jasper-runtime.jar from the Tomcat install weren't being found by Eclipse and the Lomboz plug-in. If this is happening in Tomcat by itself, it looks like either the install screwed up, or the classpath has been messed with after the install.
Write once, run anywhere, because there's nowhere to hide! - /. A.C.