First of all we need to know your ISP service, cable or DSL?
Do you know if the ISP modem has an internal router? If so, it's recommended that you bridge this modem so it will hand off a public IP address to the 4100 router so you can use it to do all the routing and operations.
If your ISP is a stand alone modem, most routers do not need additional MAC setup. Unless it's required by the ISP. I would call up your ISP and ask them if they need any additional router setup information. They will be able to walk you thru some setup if needed.
I use Safari with my 4500 router all the time. Even though DLink says it's not supported. It does work. You can also try a different browser to manage your router, i.e. FireFox, Opera, Flock. I use all three.