Seneca 36fs electrical (lighting) problem

[Laplata620]

hoping that some of you may have heard something about this and will have an easy fix!
We recently purchased a 2008 Seneca 36fs, and we're currently on our first trip (in Florida). I've pretty much managed to complete most of the work needed to avoid a trip to Camping World at this point, but this one has me stumped.
When I turn on the vanity light in the bathroom, and/or the fluorescent light in the bunk area, and/or the fluorescent lights in the back bedroom, the coach goes into what we call "Disco Mode!" And all the lights and power intermittently starts to flash (we also get a beep from the Carbon Dioxide Monitor every-time they flash).
Now, if I turn on only the bath vanity light, it happens every once in a while. If I turn on 2 of the 3, the flashes are more frequent. But with all three on, "Disco Mode" is in full effect.
I'm figuring it's a short, but from where? And why does it increase when the three sets of lights are on?
At first I thought it was the transfer switch, or a bad connection at the 50
Amp connection. But I checked all of those, and they seem to be fine (I'm not an electrician, so by checked I mean wiggled the wires to try to duplicate the effects).
Any ideas?
Thank you in advance for any help!
Jay
2008 Jayco Seneca 36fs