Well, since you mentioned it, I'll bring up an old post.
Convert your tga into jpg/gif then convert it back. (that means make your texture in paint then convert it to .tga when your finished.)
It is a 100% free, no trial version, working version. When you get it, you need to mess with the settings first, though so it will be saved into the right folder. the Url is
http://www.etrusoft.com/download.htm and click on the "Easy Graphics Converter"
(scroll down a lil bit to see it)