I searched and found some scary posts about similar problems, but here are my new button issues:
1. Pressing the trackball suddenly doesn't work, though every other trackball function is fine.
2. The Alt+Back button doesn't bring up the application switcher, though both buttons work fine independently.
3. While Alt does work, you can't hold it down and, for example, hit "R" for "3." You now need to press Alt, let it go, then hit a letter to get the number.
4. The same is true with the caps button: you have to press caps, then let go, then press the letter in question.
So, it doesn't seem like something's totally broken, but something's not totally right, either. Any advice other than get a new one?
Try doing a trackball disassembly/clean, and while the trackball is out, try using an air duster (the kind they use on computer keyboards/screens) under that general area.
I have the same problem and a software reinstall helped. however my B and X do not work and my trackball has phantom clicks. it contentiously acts as though it is being pressed in all the time.
Swap it out. If you do not carrie this phone in a holster and are experiencing these issues you've gotten dirt or other things in the keyboard/trackball mechanism.