XML for Word coding problem in Windows 10

I have an application that creates a XML file for Word using UTF8 encoding, here is the header rows: <?xml version="1.0" encoding="utf-8" standalone="yes" ?> <?mso-application progid="[login to view URL]" ?> It works fine for almost all my Windows 10 customers, but for some of them the created XML file does not contain the plain text but coded strings. For example the following row correctly created for almost all my Windows 10 user: <w:t>RISOLUZIONE DELLA RICONFINAZIONE</w:t> for some customers is created as: <w:t>?&#x02;$h&#x0A;&#x01;</w:t> And for some other customers is created as: <w:t>D&#x0B;~&#x02;$h%</w:t> Since, as I said, for most of my customers it is created correctly, I guess that there must be a Windows 10 setting to set for obtaining the correct result, but I had no luck in finding such setting. So I'll be pleased to pay who can solve this problem.