Constantly dropping internet connection from modem
I have a macbook with OS 10.6.8. I use an ethernet cable and a cable modem. My MAC keeps disconnecting from the internet. Restarting the modem does not help. When I restart the MAC I can connect again. It is not the ethernet cable (it happens when I tried others), nor the modem (it does not connect after I restart it). It may help to note that I just relaced the HD and reinstalled the OS. Help
MacBook (13-inch), Mac OS X (10.6.8)