PDA phone giving me problem

My PDA phone that I got it from my friend is actually not stable and giving me some unknown problem.

When there are some incoming calls with unknown caller, this will hang with noise come out. And I need to restart the PDA phone by using stylus pen to hit the soft reset button. My friend who is using the same model with mine, actually tells me that there are lots of defect for this device. I am quite shock with the feedback, I think this is not because of the software issue, most common will be hardware issues.

I never give up with trying to solve this problem, already try to hard resetting the device, but still the problem happens. I am seeking for the permanent solution for the problem. Since there is no permanent solution from the handphone shop itself.

Any solution will solve this matter, would really appreciated.