This is a video card problem often experienced with Intel graphics.
Possible workarounds depending on the reason for your problem:
- Make sure you are using the latest drivers
- Press "Space" to refresh the screen.
- Go to "Tools > Options > Global > Real-time Driver" and change it to the other option available.
- Resize your modelling-window.
- Set Windows to Classic Skin Mode
- Reset A:M. ("Help > Reset settings")