I remember trying to do the "Kill the eagles" quest in MM7 when playing a dark path party. I reported back after completing the quest, was told I hadn't finished, and went back to search Erathia and Bracada Desert again. I found nothing, so I searched them again. I still found nothing. In despair, I reported back a second time, and was told I had completed the quest!!!

That was one more entry in the (fairly short, happily!) list of occasions when the computer was in imminent danger of a swift passage out of the window . . .