Q: Moving the location of my itunes media library

Mac sure that on your bottom dock, the blue 'light' isn't under iTunes. Meaning you may need to right click and quit iTunes while it's consolidating. Not sure if this will fix it, but that is my best guess.

The other option, is for you to manually locate the iTunes Folder, and drag and drop it into your External hard drive.

Here is another support page that may help.

http://support.apple.com/kb/ht1449