The beep may be an error code. Watch the screen for any output data.
If you see a code flashing, write it down and call GE so they can look up the Code for exact trouble shooting.
You could also try a "Reboot", like on your computer. Unplug the unit for about 5-10 minutes and plug it back in. This might clear any errors.
A dirty or stuck keypad could also cause problems, but I think that would be more than intermittent.