Finding Removing Duplicates hanging - OSX, Network Area Storage

I can add tracks one by one to the media library, but if I try to add whole folders or just point it to my overall music folder, something goes wrong. The function to find and remove duplicates just keeps running, no matter how small the folder and even if there aren't any. I keep all my music on a wirelessly accessed network storage device (the Linksys NSLU2, for reference) which might be something to do with it, but really, I've got far too much music to be able to add them all individually! I couldn't find any option to turn off the removing of duplicates, which would be a nice simple solution, and it's not a function I'd regret losing - but then I couldn't find many options at all for the media player aspect of the program...