crash after level load

After upgrading from 4.6.6p1 to 4.6.8p2, we are experiencing a crash after loading our game initialisation scene.

I have tested 3 of our games, and we are experiencing this crash on 2 out of 3.

I have attached screenshots of the crashes in Xcode.

For builds done with older Unity versions (4.6.8p1, for example), where the crash does not occur, the next line in the log is something like:
crash after level load