Aww, Jengirl, that so sucks!! I had the same thing happen to me when I received my new Tanita body fat scale!! And, with thinking in line with Howie's, I went back to the doc's to compare, and sadly, the new scale was right. Those Tanitas are good little scales, I'm almost sorry to say.
It's an awful shock, and probably bad timing, as you were poised to get out of the 220's.....and I'm really, really sorry this happened to you. It just kind of is what it is, though. I agree with Jen that it's better to know the truth -- I'm definitely in the Knowledge is Power camp, but damned if it isn't hard to swallow sometimes. My heart goes out to you because it just sucks, but in the great scheme of things you're just going to look back on this and say, "Oh well, that was like 80 pounds ago, ancient history.....it sure sucked but it didn't kill me."
And Sandi's absolutely right: your loss remains. The fact remains that you have lost 29 pounds, and that's an enormous accomplishment, and one that this minor setback does not alter one bit. I know it really does suck, but you are so rocking the weight loss/fitness world, you are going to blow right by this little hiccup......I just know it. I send you big, squeezy, eye-popping hugs.....