i have an arduino uno and gsm shield and relay board
i first bought the gsm shield for my arduino and got it to work.never had a problem with gsm shutting down after the fist message was sent. Than i got my relay board and as soon as i put it on it would shut down after the fist message was sent.
i use tx/rx on pin d2 and d3. what i think happened is it put 5v through their and burnt out my gsm. here is a link where the schematics are link