"Use DDE" box keeps getting checked for all file types

[Guest scptech]

I am trying to resolve issues with Word and Excel files loading slowly, and

in File type associations Advanced properties for .DOC and .XLS I unchecked

the 'Use DDE' checkbox.

 

However, this checkbox always seems to be checked automatically after saving

and exiting the dialog.

 

Any ideas how to keep it unchecked?