It's not surprising that another computer on the same connection would give the same error, you're probably getting your DNS servers from your ISP. If you've got a router or anything like that, the easiest thing to do is set the DNS servers in there to OpenDNS's servers (208.67.222.222 and 208.67.220.220). That way you'll never have to configure a computer on your network, they'll get the servers from the router.
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