This topic has been raised two times. I want to add my own experience. I am a dedicated Sumatra pdf user for a very long time and never experienced any problems.
But now out of the blue I get the warning that I want to open with admin rights a non admin process. I tried to repair it with a new install as was mentioned before. It did not help much. Now I get the error message when clicking on a downloaded pdf that the document not exists!
I could not do anything else but to return to adobe.