I am facing this problem for sometime now. The default windows 10 wallpaper would suddenly be changed to blue with dots all around. I have attached a screenshot for elucidation. It would be fixed if I try to change the wallpaper. However, the wallpaper would again turn dotted with blue background. It happens mostly during boot. I'd be much happy if someone clarifies if its some bug or my display issue. Please refer the attached picture.
Regards,