Hi, I just come onto the forum to post something similar. Both KStars and PHD2 crash while in the middle of guiding. I found the correlation on 2 occasions when PHD2 lost a star then it would crash. I was able to go through the PHD2 log and see when it nose dived.
Unfortunately I am not a software person only a hardware person, so I can't place a simple idea what could be wrong and where to look at this stage.