New SOLR installation problems

[Andrew Nagy]

I installed the 12-8 snapshot of solr on my 64bit RH AS server and 
whenever I go to the admin page I get the following error:

SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.NoClassDefFoundError: Could not initialize class 
org.apache.solr.core.SolrCore

Any ideas as to what is causing this?

Thanks
Andrew