URL shows one machine, Mapped drive shows in another??

I have an Excel workbook that is updated once every morning with new data. It is then opened read only by other users to generate calculations for the remainder of the day. When I open the workbook on my machine I have UNCs in all of my Data Link fields whic is correct. When opened on one of my users machines it comes up with the drive mapping letter path.

Is there some setting that can be used to turn this off on his machine?