1. Check your Internet connection to ensure that you are connected. Click 'Start' on the desktop, click 'Control Panel,' then click 'Network and Internet Connections.' Click 'Network Connections' to check you Internet Connection.
2. Ensure that your Internet adapter is enabled. Click the desktop's 'Start' button and click the 'Run' icon, then type 'ncpa.cpl' (without quotes) into the 'Run' text field box. Click 'OK' and then click the 'Internet Connections' option to ensure that it is enabled. If the adapter is not listed, restart the adapter.

3. Reset your Internet modem by unplugging it from the power source, leaving it unplugged for about five minutes. Plug it back into the power source.
4. Remove the modem, then reinstall the modem through the 'Device Manager.' Click the desktop's 'Start' button and right-click 'My Computer.' Select the 'Hardware' tab, then click the 'Device Manager' button. In the 'Device Manager' list, right-click your modem and select 'Uninstall.' Unplug the Internet modem from the computer and reboot. While the computer is running, plug the modem into the computer. Your computer will recognize the new hardware and will prompt you to install. Click this prompt and follow the installation steps. This should remove the 678 error.