If the other solutions have not worked, and there are several suggestions on this forum, then uninstall AE, run the Adobe Cleaner Tool, Re-install AE and see if that fixes it. If not I suspect that a 3rd party codec or codec pack may be causing the problem.
Switch to the standard theme. Using the Classic Theme messes with graphics acceleration features.
I had the same problem. All I did was start Quicktime before I started Premiere and it worked for me.
John, If you have found a solution to your AE problem, please let me know. I'm in the same situation. Thanks! Holger