Wanted to see if anyone else has had this problem.
The touch screen seems to be completely non-functional when the ambient temperature is warm. For instance, it is about 90 degrees here today. When I put the tablet in the car on my way home, I couldn't get the screen to sense my finger touches to unlock the device.
I've had this issue a couple of times now - and that is the only time it is a problem.
About a minute or so after I get into an A/C-cooled location, the screen seems to work fine.