If it is of any further help, when I first started having problems, I was getting random beeping sounds coming from the keypad, as if a key had been pressed. Obviously nothing was being pressed, it would just beep merrily away.
The first time the alarm went off during the night and I was unable to deactivate it, it just seemed to be the 'Number 3' key that was inoperable, but as this was part of my code at the time, it meant that I could not turn the alarm off.
After having the system reactivated several times since, the random beeping sounds have stopped, but when the alarm goes off now the whole keypad is inoperable.
Could this point to a faulty wiring problem ?
Cheers
Baz