A couple of things, "sniffer" pens (non contact tester) are not a definitive test as they often lie saying things are hot that are in fact not. Please use a real tester, either a multi meter or voltage meter. Read both the black and white wires to the ground wire (hopefully the ground wire is in fact grounded) if you read voltage between the white and the ground then 95% + you have a open neutral connection somewhere. Circuit breaker handles do not always move much or at all when they trip, turn off all your computers and then turn off and back on all your circuit breakers. The "small spark" when you touched the black to the box makes me wonder if the wiring is on the load side of a GFI or a Arc Fault breaker, check for GFI receptacles (the ones with the buttons) that may be tripped