When I start Tomcat I get the following error:
Jun 10, 2010 5:17:25 PM org.apache.catalina.core.StandardContext start SEVERE: Error filterStart Jun 10, 2010
Maybe your application is compiled with a different JRE than Tomcat.
Check java -version on your server and then compile your code with the same version. I had the error because my Eclipse standard JRE was 1.6 and Tomcat used 1.5 - this can't work.
java -version