>If you have set up a CATCH TO anErrorExceptionObject, can you *before* the CATCH (i.e. in the main area of code) - THROW just a message .e.g THROW "Customer does not exist!" - and this then becomes the message of the ErrorException Object?

As soon as you issue a line like this:

         Throw New System.Exception("You have to login in order to use the Web Service.")

This is the last line that will be executed. That will generate an error on the client side similar to a messagebox alert.