If it is interference it could be from a number of different sources &
finding that source without the right equipment (most garage door
companies won't have this equipment) can sometimes be difficult.

Over the years I have seen interference from police scanners, ham
radio's, large satellite dishes when pointed in a certain direction,
cell phone towers, when a particular car was parked in the driveway
(believe the interference was from the car alarm), and other garage
door openers. Usually all of these items are relatively close to the
problem location. I have also heard but never seen that a TV cable will
also cause interference if not poperly grounded.

Within the last couple of years the military has been installing new
radio equipment that stomps all frequencies in the 375-450 range and
there are reports that this interference can range up to fifty miles
from the military installation. For years the Chambelain, Liftmaster,
Craftsman, Genie and others have been usuing the 390 frequency because
of it's reliabilty before these new installations. Last spring the
Chamberlain group of openers started using the 315 frequency to get
away from this interference problem. I don't know off hand what Genie
has done to remedy the problem.

About 6 months ago, most of Aruba started having interfernce problems
quite suddenly (no one there knows where it is coming from) and the 315
frequency solved the problem there also.

With all of that said, as others have posted interference will not
usually stop a closing door in mid travel. There may be some other
issue there or it may be that your aunt is holding the button too long
when she can't get the door to work & the opener actually ends up
receiving more then one signal from the transmitter.

Usually for a door company it is easier to install new radio controls
that are on a different frequency that will work in a certain area then
it is to find the offending source. If it is a military installation,
phone tower, etc there isn't a whole lot (if anything) a door company
or a homeowner can do to stop the interference from happening & the
only choice is to come up w/ a work around. It may sound like a cop out
or bs excuse but as we produce & use more products that work on radio
frequencies the interference problems are only going to continue to get
worse. Therefore until someone comes up w/ something different or
better we must learn to deal w/ it effectively & the best way to get
the consumer a product that will work as it's designed.

Doordoc