I'm on Window 7 and get the same thing intermittently. I was able to get tracking to run a couple of times, but the mask I used around a person with a forest and plant background didn't track her when she moved from side to side and I deleted them. I've tried all three tracking options. I'm using an inverted gaussian blur for the forest in the background behind the person.
I'm going to experiment to see if I can figure out the conditions where it works and where it hangs as it's currently hanging now. I would also like advise on how to get the mask to reliably track the person.