a 500 error is a generic HTTP error code and not something that gives any insight into whats actually happening. You haven't old us any information about your system, versions, etc. At this point I can only recommend taht you check your error logs and see whats getting logged there (Webserver and PHP error logs)Please help us to help you by reading and following the posting
guidelines located in this thread: Please read before requesting assistance. The more information you give us the better we will be able to assist you. Thank you.