It sounds like you maybe have different software than my DS has. The software he has starts off very easy and gets harder as you go along. After awhile it was very hard for him to pass several of the activities although he was getting 100's on them to begin with. It's supposed to adjust somehow. I don't know of anything that made him cross-eyed though and didn't see any evidence of any risks involved in the software my DS was doing. But like I said, maybe it is different. If you're concerned, call the doctor again and really stress your concern, especially if he is doing it at other times too.
