HOW

Hi - I have installed a GJD external lighting setup on a home. It has 4 zones. In the house there are two 2 zone wiring boxes and a 4 way control panel. These extend out to the garage where there is an additional wiring box for zone 1 and 2 and a remote 4 way control panel. This was all installed 2 years ago and has been working fine since. It is a great system. It has however just started causing a problem where the lights are coming on and staying on all the time. if you reset the system it will work for anything from 30 mins to 6 hours or so and then all the lights will come on usually for all 4 zones and stay on. They even come on for zone 3 which is off on the control panel. At this point if you touch either of the keypad controllers, they are locked up and just makes a strange noise. I know that there has been nothing that has changed on the install. Can anybody point me as to where the best place to start is please to troubleshoot this? Thanks