Thank you for your help.

I added the code that you suggested

            lcResultNumber = ALLTRIM(STR(lnResult))
            lnMessage =MESSAGEBOX('Error Number ' + lcResultNumber,16,'Opening File')

and ran the program as administrator as well. There was no difference - no response of any kind. I was expecting a return of some kind - in my development environment the return was 42 - on the Windows 7 portable there was nothing whatsoever.

I thought perhaps it was that the problem was in that it was in an ActiveX grid on a ReadOnly column - I removed the readonly issue and still got the same response - that is to say absolutely nothing.

Oh - by the way - Naomi suggested that I try the program in Windows Explorer instead of through the FoxPro and it worked as expected.

I find this very puzzling - why would it work on my development machine but not on my portable?