Network connection not detected

Hello all, I'm having trouble getting Windows 7 to recognize my network. I'm running Ultimate 64bit and the computer is connected to the router with an ethernet cable.

The computer has internet access and even detects other computers on the network. However the problem becomes apparent in 'Network and Sharing Center' it says "You are currently not connected to any networks". The network icon in the task bar also says, "Not Connected, No connections are available at this time". This is odd because the computer is clearly connected to the network, I have physically verified the cable is connected to the router and the computer is able to connect to the internet.

I'm trying to establish a homegroup but have been unable to do so because the computer doesn't recognize that it is connected to a network.

@aem -- I cannot connect through wireless, the computer lacks a wireless adapter

@chev65 -- I've tried resetting the router and modem but the problem persists

Any other thoughts?

When I click 'Connect to a Network' in the 'Network and Sharing Center' nothing really happens. The 'Network and Sharing Center' window flashes once then the taskbar notification comes up saying 'Not connected: No connections available'.

If I click 'troubleshoot' it runs a test to determine if there is network connectivity, which there is. The troubleshooter therefore says it can't determine the problem and believes everything is working properly.

I'm really confused by this because I know it was working at one time, I was able to specify my network location (home, public) and I was able to join a homegroup. Currently I can do neither.

Have you tried to unplug all the eithernet cables starting from the modem then plug them all back in again?