URGENT-Garry's Mod Has Weird Graphics-URGENT

Please help! I need to fix this ASAP. It’s like black edges on the top and bottom, and its faded, with 2 black lines through the middle: http://img163.imageshack.us/img163/8758/screenshot20121203at352.png
http://img641.imageshack.us/img641/5682/screenshot20121204at459.png

System Specs:
Model Name: MacBook Pro
Processor Name: Intel Core 2 Duo
Processor Speed: 2.33 GHz
Number Of Processors: 1
Total Number Of Cores: 2
Chipset Model: ATY,RadeonX1600
Type: GPU
Bus: PCIe
VRAM (Total): 256 MB

PLEASE HELP!

Does this happen in other games? Has this been a consistent problem? Make sure your “drivers” or whatever Mac uses are UTD, could also be a graphics hardware issue, I saw someone in the apple store with a similar issue

This does not happen in any other game. If this helps, I bought Gmod for my birthday last month, I played it for a week or so with no problems. Then after not playing it for about 3 weeks, I get back on and this started happening. I’ve tried to reinstall it, defrag the game files, and as well as verifying the game files. My graphics card is enough for Gmod, and I have 3 GB of RAM. 256 MB of video RAM. Any ideas on what’s wrong?

Have you tried tinkering with the graphics settings? We obviously can’t call this a gmod issue because it’s nothing wrong with the game itself, just the way it’s being displayed. Even if it only occurs in gmod, it’s not like it’s an issue with the menu or a specific map. Do you get the same effect in the loading screen? What about the main menu?

No, it’s only in-game.

Wait…have you tried uninstalling all your workshop addons?

No, how do I do that

Just go into gmod, click on “addons” then click “uninstall” on all the icons, then restart your game

I have no addons installed. I don’t know what’s wrong!

Bump? :c

This was happening with another guy about a week ago. I’ll see what I can do.

HELP!