Sorry mate, I've been on this forum for ages and I can't recall this happening before. I think that's why you're not getting much support.
I have a horrible feeling that the Nokia hasn't recognised the file format, and has decided (without asking) to try and change it into something it can work with.
I can understand your anger and frustration, but this (thankfully) isn't a common occurrence so people have no experience of it.
If it's any consolation, you have taught everyone not to swap memory cards between phones that use different file formats.