Windows is adding a route for a local address (10.0.0.90 - my fileserver) with a gateway of (10.0.0.138 - this is my gateway), the gateway only has a 100Mbs link so all of my fileserver bound traffic is being reduced to 100mbs, if I unplug the gateway it jumps back upto 1000mbs.
The fileserver also functions as the DHCP (isc) server (i am booting from iSCSI with IET and iPXE).
Also the machine with the strange route is configured via dhcp.