Oh, did I mention I work at a military installation with a big phased-array radar? Wonder if that could have something to do with it.... (kidding)Class A equipment that is designed for commercial use is allowed to produce more radio frequency emissions than Class B equipment designated for residential use. Your microwave won't cause your TV to flicker. But commercial microwaves in the office cafeteria might cause the same effect for your computer monitor!
Edit: My example was intentionally a bit fanciful. Just to be clear, any interference from a commercial microwave would be from the power supply not the heating radiation leaking out!
By virtue of their inherent design characteristics, both AC/DC and DC/DC switch-mode power supplies (SMPS) generate electromagnetic interference (EMI) composed of radio frequency (RF) signals of multiple frequencies.www.digikey.com