Protected directory error with users on Windows 10

I protected a directory on a site using the using "Password Protect Directoires" function in the Control Panel. For most people it works as it should. However, anyone with Windows 10 (using whatever browser Win10 ships with) is receiving an authentication error and is unable to log in. If they use another browser, it works fine. Any ideas what could be causing this just in one browser and, more importantly, what I can do to fix it? Thanks.