Where did you find the file?! O_O;; I can't fix it for you.. If I can't find the original.
I found the problem, but to ensure it gets fixed properly, I will need to have the original texture...
Edit; I found the original
RapidShare: 1-Click Webhosting
You will have to pick the best one out, I think it will be the MixedEdit.. but, if you prefer your own, that will be okay too.
Just repack it, and rename it, don't do anything.. and stop using TGA. Your texture was lower quality then that of Blizzard, go use BLPconverter.