I was just about to say, "the return of the Nemesis theory", except that "theory" was always too strong a word for that - "conjecture", perhaps.
The idea was that sub-stellar-mass dark companion of the Sun would pass near enough to the Oort cloud to throw a barrage of comets into the inner solar system every 35 million years or so, and that we're just about due. The name of this object would be "Nemesis". (I think Asimov wove that into the end of one of his last stories,,,)
I still like this as a working hypothesis, but I can't really see "dark matter" coming into play - unless the "dark matter" is Jupiter-sized or thereabouts.