Out of curiosity and boredom, I decided to use some of the skybox textures from Cube and make a little test level thing, since GZDoom has true color. Well, it turned out pretty damn good, except for one thing: There are these strange little light colored boxes in all of the corners, exactly one pixel in size. And I know it's not just the textures themselves, as I have checked. Here's a screenshot of said odd occurance:
I've also included the map itself, although I had to split it into two because, even rared, it was too big (damn those .pngs).
I haven't the slightest clue as to what could be causing this. I have an ATI X700 card, Windows XP, gig of ram, all that good stuff. And I haven't noticed this before, either. Odd.