it looks like you are using Jasper2.
We (Mort Bay/Jetty) have raised a bug about this to the Jasper team. They seem to be having trouble undertanding the problem.
There is a fix floating around the Jetty mailing lists for it.
If you want a really simple solution - go back to using Jasper1. With the JBoss/Jetty distro, this is as simple as swapping out the org.apache.jasper.jar - I don't know about the Tomcat distro.