First, i'm sorry for write in english, but i'm spanish, and talk in french tres bien, ut write it's difficult for me yet...desole a touts!!
I had the same problem as you, and i found a soulution...
You have to do, first of all, an installation complet avec USB; then, you disconnect your cable usb of your computer, and uninstall your live box...
Finally, you have to do a INSTALL SUPLEMENTERE avec ETHERNET..., and all will be ok, without interruptions...
i hope to help you...pour moi, ça marche tres bien..salut!