Strange dimmer behavior

Go to the CEM and do an [About] and check out dimmer 80 (while it is misbehaving) and see what the control source is.  Many systems had DMX A going from console -> to -> Arch DMX In -> to -> CEM DMX A.  Then Arch DMX Out ->to->CEM DMX B.

Is #80's drive LED (the green one on the D20's right side) on?  It could be a misbehaving D20.  I have seen the powercubes on D20's locking-on when running hot.  Try swapping the D20 (turn the breakers off, code says power down the rack...or full arc-flash protection---you've been warned) to quickly see if it is the module.

Make sure the config of #80 didn't get changed to something like a 2-wire flo, or swapped with a different module type.

I have also seen where a CC20 (constant current) that powered the arch processor, got switched with a D20, so what whenever they turned all lights off, the arch stations powered off. And when they turned stuff on with the console, sometimes the preset panels would randomly wake up. I chuckled when I figured out what was going on. 

It gets weirder! Yesterday and the day before when we switched off the console ALL lights stayed off as normal. So plan to call ECT with phone in hand was put off And then today, lamp on #80 came back on - after switch off 9back to square one). I'm printing out your reply to take in with me tomorrow and if that doesn't shed any light on the problem will call ETC. Thanks for the help.

It gets weirder! Yesterday and the day before when we switched off the console ALL lights stayed off as normal. So plan to call ECT with phone in hand was put off And then today, lamp on #80 came back on - after switch off 9back to square one). I'm printing out your reply to take in with me tomorrow and if that doesn't shed any light on the problem will call ETC. Thanks for the help.