Whoo! hold the bus, you just expanded the nature of your problem to include your com system?
That's a biggie. sounds like a cabling problem, or some other large electrical item (HVAC?) starting up and superimposing a lot of noise on the system. Possible big-time ground loop issue.
You're on to something, JD. Party line coms like Clear Com, Telex or RTS are pretty darn robust; about the only thing to take them down is physical disconnection or loss of mains power. The OP also mentioned a loud noise backstage...
Here's one possibility (speculation warning) - Somewhere on the deck the com line and DMX are run together and are being pinched, crushed or otherwise physically abused by a prop, set piece, wagon caster, maybe a door.
Another possibility - that someone mistook a DMX line for a coms line and plugged it into a belt pack. A ClearCom call signal would do some pretty ugly things to a DMX input, I'd imagine. Perhaps less so with RTS/Telex as they use tone signaling for the call light instead of DC.
The seemingly simultaneous nature of the failures is interesting.