But I do know my shocking lack of knowledge could get me burned!

At least you're not fried in a bad way.

That being said, sounds like your ballast has developed issues or something else that was sharing the breaker was off when you 1st tested but on this time.

A fridge, freezer, ac, heat, water heater or some such that draws a lot of power and cuts on and off automatically sharing the breaker could do it for sure.

And HIDs can draw several times their power when they first power up (there was a thread on that not too long ago), so if it was right below the threshold the first time, a lamp or just a little fluxuation could've knocked it over the edge.

Or the ballast could be badly contructed, shorting out, or some such.

Don't give up your good genes, though. The flouros can keep them going, until you get your flower room ready. Some folks even manage good buds with flouros. And this will also give you a chance to take some clones, before putting them into flower, if you haven't already.

Hopefully, someone with an electric mind will come along and give you some better facts about what is exactly going wrong. But you'll probably need to supply them with some even more detailed info.

Be safe and good luck!