It's because the programmers have backed themselves into a corner on that specific issue this year, and there's no way out. The problem is, you are asked to enter your property taxes twice (incorrectly). Work back through the "your home" section again. Note that you're asked for property taxes on the 2nd screen for the 1098 information, and then you're asked to enter them *again* on the screen immediately after the 1098 information screens. Leave one of them blank and you'll be fine.
