When trying to get connected ,I get this message in the toolbar,limited or no connectivity, I was using wireless and it worked fine, but when I used ethernet, I get this message, ethernet set up is >dell optiplex,windows xp, with comacast cable, netgear switch,and mac airport as the wireless. I can enable the internet connection and it will be enabled for a very short (10 sec) time, and then disconnect, please help, I am senior citizen so have patience. Should I reset the modem, unplug to reboot,? Thank you