New WSM install

Got WSM installed and managed to get three images of Win7 loaded on server. Clients only boot once then never again? When I shut them down and try to reboot the clients sit at the PXE DHCP screen and timeout. If i take a new client that has never been booted it works and I can manually enter the client details (including image to boot) and it works, Once I shut it down it doesn't work. This is a new install and I am a first time WSM admin trying to feel out the product. What am I missing?