Vista Dosen't see Router

I lost access to the internet the other day, when I ping the router it comes back as 0% lost. When I type in the address for the router in IE it comes back as Page not Found. The router is a D-Link DI-604, running Vista Home. I did a system restore and I could access the router and had internet access that whole day and the next morning, it went back to it's old ways. Other XP computers on the network never stopped working. Any ideas here?

Thanks

Did you download the Prerequisite updates for SP1???