Sometimes a corrupted Photoshop preferences file can cause strange issues like that.
Please reset the Photoshop preferences. Then restart Photoshop and try again.
If it still has the issue then go to Help>GPU compatibility in the Photoshop menu and post a screenshot of that the popup window shows. It could be your GPU driver is out of date.
Also, did this start happening after a Photoshop update?
Damon Bell
