Trouble accessing my libraries

Was trying to access my library of Rhino models and when I click on a folder I always get an error message “Class not Registered”, with a red x in a circle. The same error message for all of my libraries. :confused:

I am checking on this - no good ideas yet…


I am using windows 8.1

It was a new antivirus that I am using. Avast Antivirus.