Texture problems(Smudging and changing)

I’ m seeing textures on walls/ceilings and the ground but at a sudden point the textures will smudge or become a block matte colour. I don’t own any Half life 2 games, yet and I know error messages, pink and black chequered textures, wireframes are missing content, but with this issue i’m seeing the textures there fine then they will become as described.

Below is an image i snapped and cropped. This shows the textures becoming as shown

http://imgur.com/daIzVpf

I’ve verified Gmod files. Checked my Mac. Maybe i think getting the actual games might help and i plan on obtaining them anyway. I’m not sure what could cause it.

Any one know of it and how to remedy this?

Edit: The image doesn’t seem to load just incase http://imgur.com/daIzVpf is the link for the image

posibly running out of ram