Hey guys, I recently installed a mod which adds/changes clothes, but after I installed it with the NMM it crashes every time before I get to the mainmenu.

Anyone got an idea of the reason behind this?

The mod i installed is Z - Nocturnal Robes on skyrim nexusmods com

Sounds like a missing master issue. Check to make sure you've satisfied all the dependencies.

Which version are you trying to use? I took a look at the "black" version, and it's a horribly packaged texture replacer and the support is non-existent, with no instructions on how to install it. The way it's set up, it will install incorrectly, and even if it did put the new textures in the right folder it wouldn't actually do anything in your game, since it doesn't include an .esp to redirect to the new textures it installs and to place the playable version of the robe in the game world. I looked at one other version (the "sparkly" one) and it has the same problems, so I'm going to assume the rest of them are the same.

Try going to your Skyrim\Data folder in Windows Explorer, and look to see if there is a folder named "clothes" there. If there is, delete the folder. Try to launch the game and see if it crashes.