Well lol that's what I just tried. I convert from DDS to PNG then open and edit it in GIMP and save it as TGA... and it worked...

So it's the way the soft saves TGA files that was the problem, was the only possible reason left

Oh and about the map, it's for my mod I'm working on. We'll since we're only two right now it still can take a while... even more if I keep getting those strange setbacks lol

Well thx for your help guys !!