"Starting a few weeks ago, in a suburban neighborhood a few miles from a NASA research center in Ohio, garage door openers and car key fobs mysteriously stopped working"
NYT:
Officials from the cable company and AT&T joined the search for answers, and on Thursday, the Illuminating Company, a local electric utility, dispatched inspectors to investigate.
“They began by shutting off the power in the places where they detected the strongest reading for interfering radio frequencies,” said Chris Eck, a company spokesman. But even after shutting off power on an entire block, the overpowering frequency persisted.
...
The source of the problem was a homemade battery-operated device designed by a local resident to alert him if someone was upstairs when he was working in his basement.