Have you tried pulling the Indivision off, then pushing it back on, making sure to press very firmly? It sounds like the connection is bad between the Indivision and the Lisa chip, I used to have similar problems with my original Indivision, I had to leave my case unscrewed so I could press back down on the Indivision every day. The Mk II has a much tighter connector though, so once it's pushed on firmly it shouldn't pop off as easily, but still make sure you pushed it as firmly as you can!
