DVD file issue

Hi all, I guess I'm having a DVD issue? Photo files I've burned to DVD used to to copy, without issue, to another computer. Now they won't. The files can be viewed on other computers, but not directly copied, as before. Any ideas what happened or what I might have changed to cause this problem?

Thanks for the help!

Jim

DVD burned on PB G4 1Ghz 8x Superdrive with Toast Titanium 8,