I had the same problem which I never resolved. All I found out from Nintendo is to:
- disable norton internet security, and any internet or file sharing security you may have on, it wont install otherwise.
- Keep playing around with the settings of your internet security, they basically said to try any combination of everything
I hope for your sake that you only have to disable norton to get it to install, you can turn it on after it's installed of course.
I had to buy a wireless router to get my wii on the net. So good luck to you!