Question Author
Thanks for the responses folks.
I have done some research, and it appears that there is a difference in the way my friend's software reads the files, compared to the way mine reads them, hence the discrepancy.
I will wing my laptop over to my friendly tekkie for a look, hopefully he can sort it out for me.
Technology!!!!
Bah, and indeed Pah!!!
(as they say in the Beano!!)