Netgear changed ip, internet not working

I recently purchased a netgear wnr2000v5 router. I configured it using recommended parameters (letting netgear establish my ip) but ever since the configuration, internet isn't working anymore, even if I connect the ethernet cable directly to my computer (without going trough the router). When I try to troubleshoot the problem, windows tells me "default gateway not available" or that I should restart the router, even when it is not connected. I have also tried assigning a static ip address (192.168.1.1) but the router changes it back to 10.0.0.1... Did any of you already have that (or a similar) problem? What can I try?