Help With Some epesode 2 stuff!!!

ok just recently I got the orange box and now a lot of my maps work but… for some reason the water texture that came with epesode two is pure white!!! not anything but white… its like the texture us wrong… and for some reason my game crashes when i get to certain points in the epesode 2 campaign with gmod. say i might want to make a screenshot but suddenly I automatically exit gmod… any idea why this is??

(and yes the crashing is probablly my graphics card… I already tried getting a new one and it made gmod SLOWER than before XD)

What graphics card do you have?

It came standard with my computer… and some supposedly really high quallity graphics card made the controls lag as well as many other things.