Weird problem

Alright So I just got the game a week or so ago and I have come across a huge problem that is makeing the game hard/impossible to play/enjoy. The game loads and I can access maps, but when I get to the map itself, this happens: http://imageshack.us/photo/my-images/831/gmodproblem.png/ not only that, but the same streching effect happens with many of the objects, sometimes the objects are invisible, npc’s spawned dont show up, and my weapons dont either. I have already uninstaled it and reinstalled it twice, verified the game cache, defraged it, and it still happens. What is happening, and/or how do I fix it?

Try verifying your game cache or defragging GMod.

Maybe reinstalling gmod doesn’t clean addons and all that stuff. Try this http://wiki.garrysmod.com/?title=Cleaning_GMod

I dont have any mods

What type of graphics are you using? ATI? Nvidia? Intel?

[editline]15th January 2012[/editline]

Try adding this to your launch options in garrys mod. If you don’t know how, look at this.
-dxlevel 81 +mat_forcehardwaresync 0