I accidentally messed up some libraries in tomcat5 when trying to get JSTL working. Since my install was a default, I thought I would just remove it using apt-get remove –purge and then reinstall. Apparently, at least in ubuntu-dapper, that command will wipe out libraries in libtomcat5-java. I kept receiving this error until I also purged and reinstalled it:
Exception in thread “main” java.lang.NoClassDefFoundError: org/apache/catalina/startup/Bootstrap