the pic reset it alone

[phoenix70]

Hello friends, I have the following problem, my program works perfect, but in some badges you me reset it the pic, when I to connect the entrance of a device RS232, it is of a scale, I have designed several times this circuit without problems, not you that it can be happening, the serial exit this perfect one. I need your help please

 

 

[Technical]

Make sure the 10k/22k resistors are *always* connected to the serial download pin. This is essential for reliable operation.