DAVIDS POVI was at lunch with a business partner when I saw Selena's call come in on my phone. For a moment I was surprised and wondered what the call could be about. Because I was in a meeting, I hesitated for a moment wondering if I should put the meeting on hold and pick up her call or just call her back afterwards. But then I remembered what had happened the previous day when she could not reach me and I had almost gone out of my mind trying to call her back while unable to figure out where ...