John, ALL of the buses, or all the buses in use? By chance was the vocal on a wireless mic?
Can you replicate the problem in your shop? I can't think of anything that would make a whole bunch of stuff freak out from just turning up vox mics. Is there a chance that pink noise got routed to a vox group?
If something with the console was globally fubar I'd expect it to manifest no matter what input was turned up; if there's a problem with an individual channel it's another story.
Have you called BerryCare in LV?