I have a computer that lost it's network connection. The nic card in device mgr had exclamation marks by it so I physically removed that card and installed a different one. Problem solved until I reboot the computer and then no network connection. I run ipconfig /all and it shows a mac address of ff ff ff ff ff ff ff ff but it has been handed a dhcp ip address. I cannot ping anything except localhost nor can any pc on the network ping this pc. I then uninstall the nic from device mgr and do a hardware scan and it finds the nic, installs it, and I have network connection again. When this happens I checked the mac address and it is what is printed on the card. Reboot the computer and it's back to no network connection again. Uninstall and reinstall and I can get the network connection back up and running. Have tried the card in two different pci slots with the same results.