Hello,
Next program works fine.
I found that you are not allowed to place any command after
resume and enable !!
So, place this always at the end of the program.
Is this a bug in PBP?

@ DEVICE PIC16F819, INTRC_OSC_NOCLKOUT, WDT_OFF, MCLR_OFF
OPTION_REG=0 ' Enable PORTB pullups RB4,5 EN 6, %00000000
DEFINE LOADER_USED 1 ' Boot loader is being used
OSCCON=$60 ' osc. controller, 70=8MHz, 60=4MHz

init:
Output PORTA.7 ' Output LED
option_reg = %0
ON INTERRUPT GoTo int_routine ' Define interrupt handler
INTCON = $88 ' GIE=1, enable INTE interrupt
main:
PORTA.7=0 ' LED off
GoTo main
End
int_routine:
Disable
PORTA.7=1 ' LED on
Pause 300
intcon.0=0
Resume
Enable
' No commands allowed after here!!

Peter