Office 2013 "Operating system not configured to run this application"

[pi4711]

Using Excel and Word for years on Windows 10, all of a sudden the error message "Operating system is not configured to run this application" has started to occur on Windows 10 Build 1803 - January 2019.

Excel was working in December 2018.

1. Tried Repairing Office 2013, both Quick Repair and Online Repair.
2. Downloaded MS Office H&S 2013,
   
3. Uninstalled and Re-installed Office 2013.
4. Restored operating system to a previous update of 1803
5. Repeated 3, still no joy
6. Upgraded to Build 1809 and repeated 3, Still issues.
7. Reverted to 1803 and repeated 3. Still same issue.

Any ideas?