I am now going through something similar. Out of the blue my PicStart Plus at the office won't program 16LF819. I also have another one there and I get the same error readings. However both program 8 pin and 28 pin chips without any problem. Yesterday I took the chips home with me to program them on my programmer. Same error messages. I now have come to the conclusion that the entire batch of chips is bad because I have some older 16LF819's at home that program without any problems.