Abstract: A method for network service diagnostics includes receiving a request from a user of a computer for assistance in an activity performed by the computer. Responsive to the request, an executable program module is downloaded to the computer over a communication network, which module, when run by the computer, causes the computer to perform a diagnostic operation including sending one or more messages over the network. The messages sent by the computer while the computer is running the module are received and processed, in order to extract diagnostic information from the messages so as to diagnose a problem in the activity performed by the computer.