Hello Vince,
I had the same problem. Partially solved moving Kona on slot 4 of my macpro pre 2008 and setting slot utility to 8x on slot 4. But I still have out of sync audio and video when getting video in from analog source and also I have interferences (green flashes) on the external monitor only when capturing. It looks like a clock problem. We also changed the Kona because we tought it was broken but the problem is the same.
Riccardo Mazza