I'm starting to think I need to get my device replaced.
I keep it in the leather holster it came with.
The problem is always it can't scroll down. I can scroll up, left and right. When the trackball is replaced, it works fine- for a while. Then the problem re-occurs. One of the times I even had them clean the rollers for the trackball.
I am thinking my next move would be to ask to replace the phone itself- what do you guys think?