Have you already configured the D-Link with your TalkTalk details using the instructions that came with the router? If you have then here's what you need to do next to stop that error message and get a working Internet connection:
Go to Control Panel -> Internet Options -> "Connections" tab. Put the dot next to "Never dial a connection" and click "Apply".
Please don't forget to reply this time, and while you're at it, let us know how you got on with your previous "Unable to send emails" issue.