I don't have a 2000 anymore but I work with touch screens... There is a way to calibrate it so either search here or call tech support. If the touch is so bad that you can't even get to the calibration page, then there should be a way that you boot in to it but I assume only tech support would know that so try them.
A touch screen is normally calibrated in the shape of a plus sign, so it just means that your upper calibration values are bad. Assuming its not the touch screen its' self that's bad, this should be an easy fix for you.