Did some more research and it seems that this is the result of a blank line in the actual values of your default gateway on that particular adapter within the registry.
You can track it down if you'd like here, but only if you are comfortable editing the windows registry as improper editing of the registry can result in serious problems overall to your computer so travel at your own risk.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameter\Interfaces
All your adapters will be located under that key and the problem adapter can be located by it's IPAdress value in the right pane once you've selected it in the left pane.
Once you've identified the correct problem adapter, double click the "DefaultGateway" value in the...