Thanks for your responses

"did u try to reload the tga in the skin editor?" Yes, many times
My version of MED is 6.171. But as long as this doesn't affect how it looks in the level, I'd be fine with it.

EDIT: ok it does seem to affect how it looks in the level. So do you think I ought to save it as a 16.7 mill bitmap? I don't seem to have an image editing program that does that. Are there any free programs out there with this function?
Thanks