communication gets disconnected on msp 430f54x

My msp gets disconnected while running a routine that is using port 10 for one-run 4X4 keypad.
Is there any connection between the two?

I’ve already tried using different computers and serial ports and other cables.

at start, the coms works perfectly, but when a key on the keypad is being pressed, then the coms gets disconnected.

here is the part of the code where it gets disconnected:

   P10OUT = 0x02;
                for(m=0;m<250;m++);       //delay <- gets disconnected here
            if (( P10IN & BIT7 ) == 128){
                    for(m=0;m<950;m++);       //delay
            P10OUT  = 0x0f;     
            return 1;
                }  

where m is a local var.