Why not just burn (in Knoppix) the whole of your folder where these images are to a CD/DVD and then check on another computer they are accessible.
You can even image the whole drive if it's not too big. Though that's a bit of a waste of effort, if you only need a few files.
You can then recover the files from the CD/DVD at your leisure.
Or do you mean, Knoppix is not mounting the drive you need to get to the files?
Which version of Knoppix are you using?