@TomDart,

I want to understand what has happened ... I have some questions ...

(1) How many images on the backup CD affected? (one, some, many, all?)

(2) What software are you using to view the affected images?
(image viewer, M$ PhotoEd, Photoshop, or even
Right-Click -> Properties -> Summary -> Advanced ... to see image information)
Does it work/fail in each; any error messages? 

(3) Any error messages when reading the CD?
... Or does it take a very long time to read the image? 

--
Martin