I had to get an old harddrive back after using a newer one for a while. I had all my music on the new one with the newest iTunes on it. Coming back to the old one, it had the old iTunes, so my library wouldn't load. Went to try to update, no luck. Removed iTunes, tried downloading again. Nothing. It either will not even begin to download, or download and stop (mostly at 26% or 77%). Any idea on what to do?