Browser problem

I have a new intel iMac and have bought a Netgear wired modem router DG834, which is connected to the ethernet port. Everything about the connection seems to be ok - the correct lights light up and when I ring my ISP it tells me that I seem from their end to be connected. The only thing is, whatever URL I type into my browser (Safari, the one that comes with the computer), no pages open. My computer tells me my browser may have an 'arithmetical' problem connecting to web pages, but I really don't understand what I'm required to do to put this right. Has anyone had this problem? It's extremely frustrating, but I'm sure to those with more knowledge than me there's a simple answer. Thanks in advance.

well, it's good advice, but I've done that. So far as they're concerned, my machine connects to the net, but I open up Safari and nothing happens - it simply remains blank. They suggest talking to Netgear or to Apple about it, but I thought I'd pop in here first to see if there was anyone with any simple and free information! Cheers.