Once upon a time, I had the unpleasant experience of having a number of devices fail to program in a PC-based programmer. Some time later, much to my embarassment, I was apprised of the fact that the software by means of which the programming in that programmer was accomplished was software timed, i.e. the delays necessary to ensure that the programming specifications were met were entirely driven by software, and, having used the fastest avaiable computer with which to do my work, I was inadvertently abbreviating some of those delays. As a result, the feedback I was getting from the software's console messages was entirely incorrect.

Once I went back to the "standard" timing by changing back to a "standard" machine, I found that the devices were satisfactorily programmable.

Perhaps you should verify that you've not fallen into the same trap.

RE