My laptop has an integrated Intel gigabit network adapter. I get internet from a cable modem through a CAT5 shielded cable. The problem is that sometimes the connection drops and the computer freezes, and after a few moments the "network cable is unplugged" icon appears. Then I press ctrl+shift+esc to see the cpu usage and one of the cores is idle while the other displays a steady oscillatory pattern, and the HDD led blinks at the same frequency as the oscillation displayed on the cpu usage graph. The problem is solved by either disabling/enabling the network connecton or restarting the computer. This problem occurs at totally random moments. Sometimes it would pass 2 days without problem, other times it would happen two times in 5 minutes. I don't think it's a problem with either the NIC or the modem because if I connect the laptop to another identical modem the problem doesn't show, and if I connect another computer to the modem that computer doesn't show the problem. Could it be that noise is somehow getting in the cable (although it is shielded)? What would be the behavior of a network connection affected by noise?