Error on app that no one else is getting

We have an Excel/VBA application that has a great deal of code in it - and talks to a multi-dimensional database.  All good.  The app works for everyone except one person.  When he runs it, several pages fail with the message "Application could not retrieve the data. Please check the named ranges."  Given that I can turn right around and sign on to same spreadsheet - and it works fine for me - and we use same administrative sign on... what are we looking for in his Excel setup which could be causing this issue - as it has to be something unique to just him.  We have tested this on a dozen other machines - same sign on - same data request - everyone else can execute fine except for him.  Where do I even start to try and find what is causing this?