Recently my Broadcom NIC has stopped functioning correctly.  I cannot connect to my cable modem while using DHCP.  If I assign a static IP address the NIC functions properly.  When I use the Broadcom NIC utility, I can see the NIC acquire, briefly hold (1 second), and then drop the IP address of my cable internet provider.  It repeats this sequence ad nauseum.  I have reinstalled the driver for the NIC, done a system restore to a date previous to the problem, nothing has helped thus far.  Any assistance would be greatly appreciated.