It don't happen at every startup but I keep my fences all rolled-up. When I boot my Win10, I can see some Icons on top of the fence. I have to manually play with the roll-ups to fix the problem. I use multiple background image that switch every 30 min. Could that be the problem?
https://1drv.ms/i/s!AsrJ2e-MSJPBi_cSSqpwolF84nrn4w
Martin