HTTP 500 - Internal server error means nothing more than "There was a problem on the server". Look in the tomcat/logs directory for log files with the real cause of the problem.
It could also be that you have MSIE configured to show "Friendly Error Pages". If so, everything on the JSP end could be fine. Try disabling them. Tools -> Options -> Advanced (tab) -> scroll down to "Show Friendly Error Messages" and uncheck that item.