>         include  "handler.asm"
> alert:  
>         call     intrpt_service
>         bcf      INTCON,GIE            ;Disable interrupt temporarily
>         goto     loop                  
>         goto     main                  ;Catches errors .. we hope!
>         end

Presumably "handler.asm" is the context saving. Does it apply
at BOTH ends of the ISR ? What is the routine "intrpt_service" ?

The ISR should be something like

    <context>
    bcf   intcon,rbif
    do what you have to with the IOC value
    <context>
    retfie

Entering the ISR automatically clears GIE, RETFIE re-enables it

It seems to me the problem isn't OPTION, it's probably the ISR.
At the very least the ISR needs to be re-written so it works properly,
otherwise you've got 2 unknowns. As it is at the moment, you are
probably experiencing stack overflow because the ISR is terminated
with a goto

Also

         org       0x04  
intrpt:   
         goto      alert
         goto      main         ;**** goto main is superfluous ****

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