unknown data type?

[Oldsmobile_Mike]

Opening them with MultiView? I assume they're something obvious like jpg? There's a way to set default datatypes, off-hand I can't recall because I haven't had to mess with it in years. I vaguely recall it had something to do with editing the actual def_icons properties in env-archive...

[Oldsmobile_Mike]

Check with md5sum or similar that the files have not been corrupted during the transfer?

I would say just try to open them in a paint program or anything else that can open .jpg's to test this.  If PPaint can open them but Multiview can't, for example?

[Oldsmobile_Mike]

What's your version of datatypes.library?

Have you opened the files in a program that doesn't use datatypes to confirm that that's the issue?