GMod Map Problem

When I join any map besides Flatgrass it is always looks dark and it gets SUPER laggy. Like downtown RP’s I join them and all the buildings are black and have wierd designs on them. Same with contruct like this.
Dark: http://i766.photobucket.com/albums/xx306/Jordan589/Gmod/GModShader1.jpg
Wierd Designs: http://i766.photobucket.com/albums/xx306/Jordan589/Gmod/GModDesigns.jpg
And when I walk up to it and shine my flashlight, then it shows the buildings texture like this: http://i766.photobucket.com/albums/xx306/Jordan589/Gmod/GModFlashlight.jpg
Is it a problem with shaders? And when I open Gmod, right before it goes to the menu I see this: http://i766.photobucket.com/albums/xx306/Jordan589/Gmod/GmodWierdScreen.jpg
Any help leading or fixing this is SUPER appreciated. I basically can’t play any servers when it’s like this. Oh, here is my computer: http://support.gateway.com/s/Mobile/Q106/SonicC/1013924Rsp5.shtml

I got this when I installed freespace revolution. I deleted it and reinstalled and it fixed it.

The thing is, I don’t have Revolution and it does this for EVERY map besides Flatgrass, which is starting to get boring.

EDIT: Fixed! Lowered my dxlevel to 80