I am running Office 2013 on Windows 8.1. When someone sends me a .docx file in mail and I try to open it (either by clicking on it in the mail message or by saving it to a directory where I have my other documents and then trying to open it from Word), I get an error message something like this:
Word experienced an error trying to open the file
Check permissions
Make sure you have sufficient memory and disk space
Try opening with the text recovery converter.
This happens no matter who sends me a docx file and other people who receive the file are able to open it. I'm having no problem opening my own files or opening other attachments, such as photos that people send me.