First, go to the Security tab. Scroll over to the Restricted Sites Icon and click on it. Click the Sites box beneath it to make sure that your ISP wasn't added to the Restricted Sites.
Next check Dial Up and Virtual Private Network Settings. You most likely don't need this so delete all. Scroll down to the LAN settings box. Unless you use a proxy server then uncheck every box.
Last resort is to Delete the Local Area Connection and try to set up a new connection. Make sure you have your original ISP password before doing that as you'll need to add it again. I've thrown out both before, and it took a couple of tries adding connections to get it to work.