Electricians I need some help, or should I call Ghost busters?

[alfredeneuman]

I've never pretwisted in my life and as far as I know (reports that have come back to me), the failures could be counted on 1 hand.
I always tug a little bit on the individual wires to make sure they're seated properly in the wirenut.

 

[engineer2]

Late to the party, but the OP's issues could be a loose neutral on the incoming power line. Happened to my parents, the neutral came off the pole and strange electrical things were happening in the house.

My opinion on twisting: 2 wires will twist up fine. More, and I will strip off extra insulation, pre-twist with Kleins and cut off the excess so the exposed copper fits the wire nut nicely. The key in any case is to have the insulated parts lined up if and when when you twist.