On the P800 and have discovered a "bug" that many people probably will believe is a phone malfunction.
The problem:
As you know it is possible to calibrate the screen of the P800. This is in itself not a problem. However, when closing the flip (of the phone) the calibrated settings remain. This can easily (and might) lead to some of the small spikes on the back of the flip indeed hitting the graphical buttons but due to the calibration it will not be detected as a "pressed button". This is what happened to me. The back-button (the arrow) was not functioning until i resetted my own calibration to the factory settings.
Better would be if the factory settings always was used in flip closed mode, and the customized calibration was used in flip open mode.
I hope this issue will be addressed in new firmwares for the P800.
Regards,
Toby.