This sometimes happens, Bob. Since it actually worked right in the beginning, it's unlikely there's an electronic problem (although that's always a possibility). There are a few solutions you can try.

If the touchscreen on a Windows 8 tablet stops responding, there are several things you can do yourself to get it working again before calling tech support. If you have an external keyboard or a mouse ...

Abstract: Mechanical misalignment and scaling factors lead to a mismatch between the values coming from a touch screen panel (as translated by a touch screen controller) and the display (typically an ...