While following the Pic Elmer 160 tutorials regarding microchip microcontroller programming, I ran into a problem while trying to link a program consisting of multiple files. MPLab error message was "stack under flow error occured from instruction at 0x000000".

Taking a look at program memory it was clear that the goto Start instruction was not called and instead of that a retlw instruction was executed at program entry point. There's an easy way to fix it, just add this at the start of your main file code :

    org     0x00
    goto    Start