I get a whole lot more reliable captures when the deck is switched to the appropriate format (DV or HDV) explicity, rather than relying on AUTO. Apple even suggests that you do so:
http://docs.info.apple.com/article.html?artnum=302407
If people are reusing tapes and/or have mixed DV and HDV encoded material, then FCP doesn't deal well with the format changing while playing back or during capture.
Bill Lee