MethodInvocationException for some quick searches

A Quick Search for specific keywords generates a MethodInvocationException for SearchSiteAction.getResults().

For example, go to http://opensource.atlassian.com/confluence/spring/ and do a Quick Search for "lock" or "locking". Both produced the attached error. Searching for "locker" just comes back with no search hits.

I don't have access to the app server log file, but have attached the stack trace and system information.