I've had problems with fetchrow before if you are using a SQL function. i.e.:
select max(price) from foo where bar
In that case, fetchrow always returns something which triggers any loops to be true, but the value of what it returned could be null or intended as false. The max() function is somehow screwing with it. If I were to remove max() it would fail the loop.
That problem caused much hair to be lost on my part:)
I would be interested in seeing the query.