OH !!!! I KNOW!
Just go into your wireless router. And change the channel to 1 or 11
Bet you 10 bucks that your channel is set to 6, factory default.
If you dont know how to access your wireless router controls, just look in the book or manual. You access them through your computer, which im sure you already know since you've turned off your Firewall, but just incase you didnt, theres no switch to change the router channels on the router itself.
So i dont understand why you said "USB problems" if you have a wireless router, then the wii's wireless will hook itself up to it.
I bet your router settings are still at factory default 6. GOOD LUCK. tell us how it turns out.
Also, if your using a wireless router, set up a wireless connection on your wii menu internet options, dont go into any of the USB options stuff.