Purple textures are missing textures.
Either you did not install the full mod (sometimes, mods come as a base install and an update – you need to install both to get them to work) or you have new textures that have not been registered correctly with the game.
Which method of Archive Invalidation are you using ?
If you don’t know, chances are you are not using any
Try this one : Archive Invalidation Invalidated!
Download, follow the instructions and completely forget about it for future mods.