I just encountered the same problem. Everything worked fine this morning. I got home from work and all of the buttons on the touch screen will not work. I have had my unit for well over a year and have done no firmware upgrades. When I touch the display the light comes on but that is it. I have the battery pack, and tried removing that, also tried reset button, no luck.
Reading through this post it sounds like a lot of people are having the same problem all of a sudden.
If anyone has any suggestions, please reply