DotCMS install to existing tomcat errors

Question

I'm currently trying to install dotCMS to an existing tomcat installation. I've extracted the war and dropped it into /webapps/ROOT in tomcat. I've edited the ROOT.xml file to point to the MySQL database I have set up called dotcms. When starting tomcat, the database is created by dotCMS and this appears fine. When trying to login however, I am getting the following error:

24-Nov-2011 10:46:40 org.apache.catalina.core.ApplicationContext log
SEVERE: Error loading WebappClassLoader
  context: 
  delegate: false
  repositories:
    /WEB-INF/classes/
----------> Parent Classloader:
org.apache.catalina.loader.StandardClassLoader@1af33d6
 org.apache.jsp.index_jsp
java.lang.ClassNotFoundException: org.apache.jsp.index_jsp
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1095)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:809)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:129)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:619)

I can only assume it is missing a jar or not looking in the correct place?

Hopefully someone can shed some light on this one for me.

Thanks!