Wii internet problems

I'd been having troubles connecting my Wii to my internet for some time. It was having problems recognising the WEP key I used. So I removed the security from the internet and tried connecting it again. On the display box which shows which internet you want to connect to when using Auto-Search my internet showed up with a blue unlocked padlock. This means that there's no security on it right? I connected to that one and when it tried a connection test it came up with Error Code 51330. This code means that the WEP key has changed or is incorrect. Can someone help me out?

Do you have a firewall on your PC? Have you opened up the required ports to allow the connection to the Wii. Who is your ISP?

That's a good idea about the firewall, I'll check that.