Imac problems possible corrupt library

So as I'm getting a new nas for movies as my TV one is getting full I thought it would be easier to use my imac as the server and just mount the nas drives. I didnt think it would take long as most of my album art etc I used was just the default. But I'm having some issues where the dash board won't load ever. Last time this happened on my nas I just deleted the library and re added it but I cabt do that this time as it says there was a problem deleting library. I've tried cleaning bundles and emptying trash. It also says there is a problem optimising library when I try to do that. Please help!!
Thanks in advance :)