software update connectivity issues

Help please. I installed software update for my macbook yesterday(Safari iTunes, Java and one other I think). Now I can't connect to internet at all unless I use Network Diagnostics, restart my modem and router every single time I boot up. My son's iPod Touch won't connect either. My other son's macbook does not have this problem and works fine because he didn't do software update installation. Any suggestions on how to fix this problem? I have tried ethernet cable and airport connections. Same issues. Thanks.