Black and white pixel/texture bug

I need help! When i play on the map wich is on an server an irritating bug/glitch appears. The whole map is covered with pink and black pixels/textures! Ive tried to rejoin the server, restart gmod and ive reinstalled it. But nothing helps! Please someone tell me what to do! I dont wanna start playing at an other server beacuse this one is so awesome! Please help me! And one thing i wrote wrong… Its not black and white. Its black and pink.

EDIT: Never mind i fixed it! :D:D:D:D:D:D

what map is it
what games do you have

I have: CSS, Half life 2, Half life 2 Deathmach and Day of defeat. The map is called: Ass-westwood something. The map has worked properly until this day…