Forerunner 945 Restarting when snowboarding

I've used the snowboarding app a number of weekends recently and have discovered that while in the activity the watch tends to restart itself. I was wondering if anyone else had experienced something similar? 

Essentially I would start the activity, GPS would go green and away I would go. I'd head down the mountain and reach the bottom, hit the lap button and then get the chairlift back to the top. During the chairlift ride, more often than not the app would seem to 'auto' stop . When I got back to the top and about to head down again i would hit the start button. On every other start of the run when I hit the start button the screen would go black, the Garmin triangle symbol would appear and then the loading screen would also then come up (with copy rights, maps loading etc.). once this was done it would go back into the activity. Fortunately every time it wouldn't lose any of the logged data (km's, time, duration, elevation etc.). The annoying thing is though that I would have to wait for this whole cycle to happen before kicking back off again and then at times it would reset during the activity and i would get to the bottom with the activity being paused. 

If there is a known fix or idea of what might be occurring, some help would be appreciated.

Cheers