Well, I have no clue what the problem was. I ran into the same problem with GIMP, but found that simply resaving the files as TGA with IrfanView made them GIMP-readable. So I batch converted the whole lot from TGA to TGA with IrfanView, loaded a couple in the GIMP, and it looks like that fixed it. When I copied the files over it looked like the converted files were slightly smaller than the originals, so maybe there was some kind of alpha channel getting involved.
I've attached the same file so you can try it out under Linux.
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