Med
The only method in the code you posted that can generate a ServletException is the forward method. forward method only generates one if the resourse it is forwarding to throws one so the actual Exception is coming from the JSP your forwarding to.
From what the error message says I would double check to make sure the request and response objects you're forwarding are HttpRequest and HttpResponse objects. Is the
servlet an HttpServlet? And are the req and resp varialbe the same ones you are passed in the doPost method?
If all of that is ok then post the entire doPost method and that should help.
Also, and don't take offense, did you modify the _jspService method in any way?