Issue with materials and textscreens

So, I’m very new to Facepunch. As I can’t find a fix for this, I decided to make an account here and try my luck.
Here are a few screenshots of the problem.

http://cloud-4.steamusercontent.com/ugc/534013634094014324/CDFA4265D6510A4823336B6486BDBA49C2E8BB06/

I cannot see ANY material on any prop

http://cloud-4.steamusercontent.com/ugc/534013634094013481/E8A65BED870DC0500E8ABB7D632636107AD1B8B5/

My text screen has a box (which should be invisible) showing

I have tried uninstalling all my addons, but it simply won’t work…
Help?!