Still can't get past the "Project Cannot Be Upgraded to the New File Format" error message

I get this message when I try to import audio. I tried all of the items in the below article. I even created a brand new powerpoint file and brought in my slides from the course. After doing that, I was able to import audio for a short time. Now the error message is back. How do I get the error message to go away permanently?

9 Replies
Beth McGoldrick

Yes, I did a repair - everything that was suggested in that article. Then I
rebooted my computer. Then I still got the error. So I brought the slides
into a blank PPT and was able to import audio for a little while, but then
today am not able to import audio again in the newly created file.