Coincidentally and bizarrely (timing wise), I have this exact same problem and was just searching the forums to see if anyone else had experienced it. The main and page buttons wake the device, but they won't actually return me to home or change pages in the current menu. It sounds like you and I have tried most of the same things with no luck. In addition to what you've listed, I also tried resetting the device with the reset button inside the battery compartment to no avail. My next step is to take the thing apart and see if I can figure anything out.

Please post here if you do find a solution, and I'll do the same.

TheEndless