Hi Whitney,
Since no one else is biting I'll throw in my two cents and advice. I guess just to ask the obvious question, have you or anyone else successfully used this board and setup in the recent past, or is this a once or twice a year deal where the system spends most of its life in a closet or storage cabinet? I'll admit that I'm not terribly knowledgeable about this make/model of light board, but is it possible to do a factory reset?
From what you're saying it could definitely be something with the board, but what else is in between the board and these lights? Any dimmers per chance or are these LED lights? Though rare, I've dealt with one or two instances where a dimmer basically lost its mind! If dimmers are in use (which I suspect they are), what's the make/model and how many do you have? If you have multiple dimmers I'd suggest setting all your dimmers to the same starting address to rule out a dimmer glitch.
The Channel 2 issue almost sounds like you're tripping the breaker or causing a fault on the dimmer. Some dimmers will self-reset when the channel is returned to zero for a little while and will cause a very similar result. Let us know and hopefully we can figure this out!