Skyboxes and fence-like texture prob

When I load up GZDoom and go to an outside area there is no skybox displaying and fence-like textures have a problem, too, ex: doom 2 level 1, I go to the left to get the chainsaw and the spaces between the bars are light blue. help.

http://forums.newdoom.com/showthread.php?t=34806

EDIT: Oh, wait, I see you answered over there.... Yeah, it definitely sounds like a graphics card issue. Hopefully the new one will fix it. :)