You seem to be having issues with crashing as it is. And yet nothing you have said suggests that custom content is necessarily the problem.
It is possible that you have a video card that can occasionally be overwhelmed. That happens to me sometimes too albeit very rarely. If it is a video card issue I don't believe you can do anything about it. Since it is rare for me I ignore it. Others may have recommendations for you. But if your next few play sessions are crash free, I wouldn't worry about it.
With regards to whether you did anything wrong: Erasing the .7z suffix on the files you downloaded rather than extracting the files ( .7z is the suffix for 7-zip archives ) was not a good move. I assume that you subsequently figured out how to extract them, but if you are doing these kinds of things often, it is very hard to assess what is causing the crashing or even if you are playing the Enhanced OC at this point. I don't say this to you to cause a freakout, but rather to encourage you to read some tutorials on how to do basic things with your computer. With anything that I do I research tutorials on line and follow them step by step. I think this would be a good practice for you.
