Swithing with itunes and an external harddrive.

Okay, so I recently switched to OSX. I've always kept my music on an external harddrive, and I decided to use my Mac to update my iPod since it would be faster. Once I plugged my external harddrive into my Mac (The iTunes library was already made a few days ago, by the way) all of these new folders just began appearing. For example, I have a folder called "P.O.S" and another one called "P.O.S_" appeached. In the second folder, two of the songs that should be in P.O.S were there. Does anyone know what's going on?

I think I'm beginning to figure it out, it seems like it's only happening with folders with odd punctuation and "And" or "&".

OKAY, crap. I just began updating my library with a folder and it's decided to make a folder for all these songs that shouldn't have folders associated with them...how do I stop this?