Hi,
I have experienced what appears to be the same issue. I loose manual focus control after switching back from auto focus. The problem is not easily replicated and has occurred 4-5 times over about 2 months of intermittent use.
I have to switch the camera off and on, this takes time but it has always revovered function this way.
The problem has been as live events (a Team Extreme Sports event) last week where I had to loose footage while down.
I am hoping that there is a fix, my impression was that this was a software issue as rebooting sorted it.
Rob