I have the same problem. Every single time I watch CBS All Access on my roku it crashes and reboots the roku. It reboots just once, usually just a few minutes into the show. I can watch multiple episodes in one sitting no problem. But if I exit the CBS app, and restart it then it does it again. I only have this problem with CBS All Access - no other apps that I use.
Thanks for the inquiry.
Try removing the channel from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel'. Then restart your device from Settings>System>System restart. Once your player starts up again, add the channel back once more.
Does this clear up the issue you are seeing?