A witness told us, "Ed was furious the network was running election-night promos and he wasn't in them. He'd been arguing on the phone with marketing, then he slammed down the phone and exploded. It was like Mel Gibson had entered the newsroom."

Schultz was immediately dragged in for a meeting with NBC News President Steve Capus and MSNBC President Phil Griffin following his Aug. 12 meltdown.

Our source added, "Schultz was told: 'If you do that again, you are fired.' He broke down crying."