I had a similar problem in a PC with Arabic windows, some users install the Arabic keyboard language but the ”Language for non-Unicode programs” setting is kept default to “English”, if the file is located at the desktop or document folder (and the user name is in Arabic), or any path that might have a folder named in Korean it might cause a problem.
You can instruct the user to move the file to c:\ drive or “c:\any all English folder path\format.xls“,just don’t open it from desktop.