I also have been getting the audio error messages. Updating to BlackMagic 6.4 drivers helped
(reduced the frequency) but did not eliminate the problem. I use AIFF only, and it doesn’t matter what is selected in Preferences (Line Out or DeckLink) The error message comes
after a RAM Preview playback and says “UNABLE TO START AUDIO HARDWARE” This started
ONLY after updating to CS3, and was especially frequent using BlackMagic 5.6. I’m on a
Mac Pro Quad (PPC) 2.5, 8.5 gigs Ram, FCP 2.0, CS3, BlackMagic DeckLink Extreme.