Here is a pretty strange situation.
I have a MacMini running Leopard that is connect via Wifi to my router/internet. Using Firefox, I have no problem surfing the web, and using Adium, I have no problem accessing my accounts and chatting.
However, any Apple product, such as Safari, iTunes, Apple Update, etc... can not access the internet. It says the network is not responding. It asks if I want to use the network connection troubleshooting utility, so I select 'Yes' but it says all is well.
I have also made sure that the firewall is set to allow all connections. I have run the repair disk utility, and I also created a new user, and the problem still persists. Anyone have any ideas?