My game will not open whenever I add a new mod.

I had something like this. I removed the 'mods' folder to desktop and ran the repair on a clean game. It worked fine.

It was then the grueling task of tracking down the glitchy CC content by installing mod files one by one. Cross checking for latest versions, or if I'd messed up the install. Long and boring. Luckily, I don't run much CC content so there were only 50 odd files in total.