Signal found, but no connectivity

Try this. It should renew your configuration between your router and your internet provider:

Step 1 Log into the web-based configuration by typing in the IP address of the router (default:192.168.0.1) in your web browser. The username is admin (all lowercase) and the password is blank (nothing).

Note: The 192.168.0.1 address is NOT on the internet. It is the address to the router itself.

Step 2 Click the Home tab and click the WAN button. Dynamic IP Address is the default value, however, if Dynamic IP Address is not selected as the WAN type, select Dynamic IP Address by clicking on the radio button. Click Clone Mac Address. Click on Apply and then Continue to save the changes.

Step 3 Click on Status. Under WAN, Click DHCP Renew. If it does not get an IP address or times out, then continue with Step 4.

Step 4 Power cycle the cable modem and router:

Turn the cable modem off (first)
Turn the router off
Leave them off for 2 minutes**
Turn the cable modem on (first)
Wait until you get a solid cable light on the cable modem
Turn the router on
Wait 30 seconds

** If you have a Motorola (Surf Board) modem, leave off for at least 5 minutes.

Step 5 Follow Step 1 again and log back into the web configuration. Click the Status tab and click the Device Info button. If you do not already have a public IP address under the WAN heading, click on the DHCP Renew and Continue buttons.
If you're still getting no connection to the internet, another alternative (before chucking the router) would be to reset it to factory defaults, and run through the setup process again, from scratch.

Cheers