Okay, I've already updated my drivers and ♥♥♥♥ to try and fix it. But while playing Source games, my drivers crash and the screen goes black with the audio looping for around 5 seconds. And it usually does this non-stop on L4D, maybe once a minute on Garrysmod, and only once or twice during a several-hour play session of TF2. Anybody know how to fix this? I can't even PLAY L4D anymore, and Trouble in Terrorist Town, my main G-Mod gamemode, well, I get killed a lot in that from this as well.

Honestly, you'll have a lot more luck finding a solution if you ask on the Steam Powered forums. They have mods who know what they're doing and may have even heard of the problem before.
Try this: https://support.steampowered.com/
Then post your problem Here if you can't find a solution with the above link.

I've already looked around and none of the solutions I've been given have worked. And by 'solutions' I mean the following statement: Update your drivers and it should work fine. So, you see, I figured maybe one of the members of THIS forum would have encountered the problem before, and had found a better solution that actually worked.

Check your voltage.. Same thing was happening to me while i was Overclocking my CPU. Not enough voltage on the GPU and drivers crashed, reseting the GPU.