Ooh, I have come across a possible answer but it's very fiddly..
The reason you can't view the file on the camera is because the EXIF header data built in has been changed (possibly stripped or otherwise altered when the file was saved on a PC). This is information built into the image file itself and the camera uses this to know what it's got and how to show it. If this data isn't perfect the camera won't read it.
It would seem that it's possible to copy EXIF header data from one file to another. Like I said, it's fiddly and there is no guarantee it will work at all. I would also suggest that, if you try this, you try it on a copy of the photo. The last thing you want is to end up with a completely unreadable photo.
The link to the software to do it is
here