Hi Mister-e,

It wasnt a low voltage problem.

This one could program any device at any time but with this specific code the pic could no be programed ever again.

I think that was mentioned that the program burned sets some pins in a way that the programming pins cannot be used to re-program the pic.

It was also mentioned that this phenomenon may occour when these pins are programed this way combined with using the internal oscilator.

.