by ric » Fri May 29, 2015 11:27 am
I think that's a good guess Susan, but the opposite way.
LVP should be disabled. If it's not, and if the PGM pin is not pulled low, then programming can be randomly disrupted.
The problem will come and go, depending upon ambient humidity, temperature, and electric fields, which all affect if the PGM pin floats high enough to cause problems.
Latest test project, an LED matrix display made from one reel of addressable LEDs.
here