Search Engine Watch Forums Moderator, AussieWebmaster, started a thread at Search Engine Watch Forums describing weird behavior he has seen in some of his AdWords accounts. The behavior is described as keywords activating and inactivating by themselves in the course of a few hours.
This is not just a one shot deal. AussieWebmaster, Frank Watson, describes this issue over a period of "a few weeks."
So imagine that, you have some long tailed keywords (three or four word keywords that have low impressions by nice click throughs). Throughout the day some of those keywords turn to inactive in your Google AdWords console. Then a few hours later they become active again. This phenomenon repeats itself time and time again over the course of a few weeks. What is one to make of it?
Perhaps Google was testing some of the new quality score algorithm out on some keywords?
Forum discussion at Search Engine Watch Forums.