Zune to iTunes.

I want to put all of my music from zune onto my ipod, so I found a way to transfer it off of zune just into a file on my computer. Whenever i plug my ipod in and that file is open a little icon that looks like an ipod and says Apple iPod beside it pops up on the side of the file. I highlight all my music, drag it over to the ipod, and let it go. It always starts copying the music but then stops and something pops up that says my ipod has either stopped responding or has been disconected and I'm not too sure why. Any thoughts.