Error when starting Solr using Tomcat V6 (tomcat6-6.0.13)

[Hong, Dan]

Hi,
 
I'm getting the follwing error when starting Solr:
 
java.lang.ClassNotFoundException: org.apache.catalina.startup.Catalina
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at
org.apache.catalina.startup.Bootstrap.init(Bootstrap.java:215)
        at
org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:390)
 
I do not get the error when using Tomcat V5 (jakarta-tomcat5-5.5.20)
 
What could be causing this on the newer version?
 
Thanks,
 
Dan