This happens to me, and it's not an Ipac issue for me. Sometimes, when starting everything in my cabinet from a single switch (and with "Power On after failure" turned on), it fails to recognize the keyboard / Ipac and will give an error saying so. After a moment, it will continue into windows and I won't have a keyboard or Ipac. A restart solves this, and with my new PC, it has only happened twice, but with my old computer, it happened quite a bit.