sleep mode / wake up and strange graphics on screen.
New computer and after 3 months the sleep mode/wake up takes forever to wake up. When it does the screen has a psychedelic pattern and you can see the underlying website, etc. after about 2-3 seconds or hitting the return key it goes to a lighter pattern then finally back to the screen. What is wrong? How do I fix it. Really frustrating to have a major problem on a new computer. I hope it is simple to fix?
iMac 27" 5K, macOS 10.14