I've gone through two touchscreens on two separate XFR's running XP Pro.  They just abruptly stop working within a month of each other.  I can open the Dell Touchpoint Controller and the USB entry is no longer there.  I have been unable to re-install just that driver and have to correct by a full system restore.  Does anyone have an idea as to what might be corrupting the touchscreen driver or had similar problems?  

Thanks!

David