Since I bought the cam I have the same issues. Didn't really noticed it until I used the car for a very log drive.
It used to start up and record (the LED would change between blue and red). After approx. 15 Minutes cam goes off and the blue light is on the whole time. I switched off motion detection - nothing changes, I switched off the "automatic power off" and at least for the next 3 days everything worked properly. Now, the same **** again.
I'm pretty pissed, as I thought I've finally found a very good, reliable and cheap cam which covers everything I need, but with this AND the wrong speed readings through gps, I will have to send it back. I guess cheap, reliable and very good doesn't work well if used together.