I'm joining this board in particular to tell you that I have had that same experience (machine won't quit sewing). I have a Janome DC3050, one year old, and it did the same thing. In fact, it did even more than just not stop. It would start sewing all by itself when I wasn't even at the machine. I took it in for repair(which is free where I bought it, for life) and they fixed it but I never did find out what the problem was. Since then, it's been working great. Was glad to hear some one else had the same problem. I think they thought I was crazy - happy to find out I'm not! Good luck.
donnal