This post is more than 2 years old.
So, I'm still kinda new at this Java thing. I'm working on my first real JSP based web site, and ran into a problem that I couldn't fix today. The only change I had made in the past week was to update the Java SDK from 1.3.x to 1.4.x. What I forgot - though - was that I had many JSP files already compiled by Tomcat. My coworker AJ pointed out that I should delete the compiled files in my work directory. So - I did that - and restarted - and it worked perfectly. I also remember this suggestion from others in the past.
So - in the hopes of helping others, I'm passing it on here.