Solved Last night's Windows 7 Update, grabbing 192.168.123.xxx IPs now

Came to the office this morning and all the Windows 7 machines dropped off the network after a Windows update last night. No other machines (Mac, CentOS, Ubuntu) were affected. I had to static the IPs on them in order to get them to connect otherwise they would just grab 192.168.123.xxx IPs.

Turns out we had a rogue router plugged in backwards and after the update, pushed its own DHCP before our server's.