hello mate,
I have the exact same set up as you, Mid 2010 pro and upgrade metal graphics card, and wondered if you had any luck with sorting out the playhead position issue. I'm also finding the transport rewind/forward wind controls freeze the playhead. I notice that the HD usage level peaks when a try and fwd or bwd wind.
Wondering if a control surface like faderport might be a workaround....
How did you get on?
Cheers.