[QUOTE=Acetronics;36807]Ah, ...

Last but not least ...

is MCLR configured as "internal MCLR" ... ???

Thanks for the reply Alain,
I modified the inc file and set MCLR_OFF.

I've since refined it, it has nothing to do with the blocks of code. Pulling GPIO low slows the chip down. It has this effect on the simplest of code (flashing led). Tonight I'll write something in C to see if it's a language thing.
The circuit is a friends, I'll draw a schematic from the board layout and see if he's done anything hinkey..

PK