Good afternoon,
Based on the snippet below i would say that one or more classes are not available.
Please review this link.
http://www.ibm.com/developerworks/library/j-jsf2/

In regards to the classcastexception, we could only tell for sure what the issue is with a classloader trace.
However, I would look for jsf realted jar files and see if this may be an issue.
Hope that helps.