Xbox 360 Internet issues?

Last night I went and turned on my Xbox 360 and it refused to connect me to Xbox Live. I had last been on about 30 minutes before and it was working fine. My console is connected to my router by an ethernet cable and when I test the connection it tells me I am connected to my network, but not the Internet, and tells me "Your DNS server cannot resolve the names of the Xbox Live servers". I've restarted both my router and modem about a thousand times now and no success. However, my computer across the house works fine. I checked all my settings and they are fine. It's been more than 12 hours since then, still offline. What's wrong with it?