When using the MCSP bootloader you have to understand that it is the CONFIG of the bootloader .hex file that you initially flashed into into the PIC that's "in play" and not the CONFIG in your source file. The boorloader will completely ignore whatever CONFIG you include in your source file.

IIRC the bootloader(s) are setup for external x-tal. Your schematic indicates that you don't have one connected and your code indicates you're expecting the PIC to run on its internal oscillator - which it won't IF the bootloader dictates otherwise.

Some PICs allows you to change primary osillator at runtime but I don't think the old 2431 is one of them.

/Henrik.