Write Error: Error writing sub-document content.xml

I get this error any time I try to save a document. I can Save As and change the name, but I cannot save the original file. None of the files have pictures. Some have comments, but not all. I’ve had this computer for nearly a year without trouble until the last monthish.

It started with OpenOffice, so I thought maybe if I changed to Libre my problem would be fixed.

The first file I saved gave me the error.

I haven’t had trouble with WPS yet, but nearly all my files are in .odt which WPS can’t read.

It probably is a problem with my firewall or settings somewhere, but I don’t even have the first idea where to look.

I’m an author. This is a big deal to me. Help.