BMW R100RS, Double video fail.

I had to take the BMW out for a short ride to warm up the drive shaft and the final drive oil ready for changing. I put on my chest mounted GoPro, didn't think the helmet mount worked very well last time and off I went.
When I got back I realised the GoPro had frozen at a very early stage of the ride, and what footage I caught was too low. Too much bike and not enough scenery.
I've no idea why the GoPro freezes. Software up to date, SanDisk card fastest one they have.. tried all sorts of things, vibration shouldn't be bad when chest mounted.. I'll keep trying different things, fingers crossed :-)