I always keep mine set to auto pause when < 3 mph. If you are metric, then probably the option is when less than 5 kph, though I think it's also customizable to any speed.

When I had my Edge 500 auto pause use to do quirky things until I set it to that. I set my Edge 530 to the same when I got it. I've not been out today, but it's been good since. If you recently had a update, you might just do a reset. It's an option given by power button when you hold it for a time or some how I get to it when pushing the power button.

Is this on routes that you done before and had no issue? Might also consider if you recently put a new video camera next to your Edge or a flashy thingy (a light).