Hey guys, this might be a stupid question, but what if his kitchen isn't original? If added-on space, any possibility that the drain pipe runs straight out of the house rather than through the original sewer line? I'm curious about this business of all the other drains working fine. Granted, it could be a disposal problem or foodstuffs-down-the-drain problem, but I figure a guy who's snaking out his own pipes probably gave at least passing consideration to that. I'm thinking more along the lines of a problem further out the drain line, but can't see why it would only effect the kitchen, unless there's something hinky in the construction, or an invasion into the line closer in. It seems like there's got to be a logical answer (short of getting a divorce, Wick! Not that my friends and I can't use the business . . .).
Poster, do you have willow trees in your yard (or a neighboring yard)?