As oddly as it started, the widespread problem with some garage doors in the Ottawa region had disappeared by Friday.

The powerful radio signal causing the problem stopped transmitting on Thursday afternoon, around the time CBC News contacted the U.S. Embassy to ask if it knew anything about it.

The embassy categorically denies that it had anything to do with it.

The signal was being transmitted at 390 megahertz, a U.S. military frequency used by the Pentagon's new Land Mobile Radio System. The same frequency is used by garage doors openers, which started to malfunction around the city about almost two weeks ago. A similar problem has popped up around military bases in the States.

The world's biggest garage door manufacturer, the Chamberlain group, took the problem seriously enough to fly design engineer Rob Keller to Ottawa from its Chicago headquarters, with machinery to try to track the signal.

But by the time he got here, the signal was gone.

"Well, as you can see there, we're not picking up anything there, which is the way it's been since I got in last night," said Keller Friday. "But there must be something out there, so I'll keep on it the rest of the day."

Industry Canada also sent its inspectors out with a sophisticated direction finder, says Ontario spectrum manager John Baggio.

"By the time they actually got out there to investigate the source, it had ceased to operate. So it's not possible to direction-find the source unless it's actually active," he said.

And people, such as Judy Dougherty, suddenly found their doors, which had been jamming for 10 days, were working just fine Thursday.

"Finally, [Thursday] night, ta-da, it worked. So there was no logical explanation. We said, 'Well that doesn't make sense.'"