If you have Patch 2.02, this should fix it (solution found thanks to Necro and SilverElf
)
To fix the 2.02 V7 - Edain conflict you have to find your Rise of the Witch-King Installation Folder (where you installed 2.02) find the file named !vanilla202music.big and rename it to vanilla202music.big This will remove the priority for the file and therefore stop it from overwriting key Edain code. If the player has custom 2.02 music enabled then will need to rename !new202music.big to new202music.big instead.