Back in business

I went online and found a site for trouble-shooting the failure to boot up a MacBook Pro. It proved easy enough-press the power button and hold down the Option-Control-P-R keys. It worked. Then I went to the library and assured myself all is well. Came back home and went to the upstairs bedroom - which is not being used as a bedroom right now, but where in past years I've used the laptop all the time. It is more like a store room now. Computer works fine there. So that strongly suggests that our current bedroom, which is in the basement and right next to the furnace room, and is where I've been having computer problems, is within the electro-magnetic field of some piece of equipment, a field that extends to the living room-dining room area, where I also have problems, but not to the second floor bedroom. So I can do computer stuff upstairs and won't have to always go to the library. There is a table and chair there right under the window.

What is a mystery is why this presumed "field" doesn't seem to affect the iPhone, and doesn't seem to affect Paul & Jenny's Dell laptop. Just my Mac. Any suggestions anyone?