Welcome to the Community!
There are some things that we may need to check and consider to identify what is causing your issue:
1. Is the file that you have dragged on your backup disc corrupted?
2. Is there a compatibility issue with the file:
If you can provide us more details of your issue then we might be of further help.
Thanks for your reply Moderator. The tecnician had updated my System and that proved to be the cause of the problem. I returned to computer to him and , five days later, he had juggled things so that the files now open. Thanks again, Evan.