Great advise guys, but BEFORE spending any cash on fret work, PLEASE check the string itself. I do some side guitar setups and stuff, and on more than one occasion, I've had a friend come in with a "dead-note" on a string, and the string was bent in such a way to make it die out when he bent it. His cat bit it or something.
Definitely worth checking before getting into fret work.
And as I said, I've also seen a case where the pickup was too high, and when the guy bent the high E, it would fret-out. But that will usually happen on more than one fret.
All that being said, it's probably a high or low fret as Rich said.