Well it could be to do with the way Vista is handling files. If you could
view them before under another OS, then it's not likely they are corrupt, or
there is such a tiny amount of corruption in them that the picture is
unaffected and some program is over zealous on handling errors. It could be
simply the way the file header is written by the program that created the
file.
If you happen to be reading these from CD, it is possible your CD is
damaged, failing, or the files were never written properly in the first
place. I have seen CDs people write that they never bothered to verify
before deleting the files from the HDD.
It can also be a chipset driver problem causing the files not to be written
properly to the HDD, though I woud expect this to affect most files on your
PC, and before too long the OS.
Try these files on another machine running Vista and see what happens.