Alright, please, I could use some help.
Yesterday, I turned 15 and I got Gmod as a birthday present later in the day. Got on sale for five bucks. So, I download it, its all fine and dandy. Then, when I try and launch it, it comes up to the loading screen for a few seconds, and then minimizes down to the desktop with a black box covering on quarter of the screen in the top right, and an error message saying hl2.exe has stopped working.
Now, I have L4D2 installed on my computer, so it DOES have a source system for it to use and run properly. Can anyone tell me how to fix this error?