Wow that's really freaky. Even with my mish-mash of components (DA-7900 10-sp crank, DA-7700 9-sp everything else), I've had zero issues, even with me having done the assembly and adjustment. Funny thing is, my last bike (DA-7700 everything) would drop the chain to the inside of the small ring at the drop of a hat. It was so bad that I installed a K-Edge chain guard, which solved the problem.

I left that chain guard off the Emonda because I didn't think I needed it anymore. Maybe I was wrong.