You need to start by ruling out mods. If you use a mod manager, you can quickly disable any texture mods you have, like NMC, etc (you don't have to uninstall them, just disable them temporarily). Then open the game, see if problem is resolved. If so, you know it is one of the mods, and you can go about pinpointing which one. If problem is still there, however, it may have to do with your graphics settings, etc. Try this and report back!
No way, man, I don't do signatures.