As I mentioned before, I spread X2 over two monitors, so use them as one big monitor, and have not had any problems.
To help the OP out, I tried to follow his workflow, and discovered that my Sonar crashed every time.
I'm busy working away in another studio for the next fortnight, away from home, but will pop back when I return.
Again, Maybe this is why one person finds a program buggy, and another finds bug free.
For the way I normally work, Sonar X2a is as solid as a rock.