MDT not proceeding to Deployment Wizard after entering credentials on target machine

I have a server configured with MDT 2012 and am using WDS on another server with DHCP and AD to push that out to client machines. Sometimes it works, other times I enter the network credentials into the wizard on the deployment client and instead of saying 'Processing Rules: Default' and proceeding to the task sequence selection, it says 'Initialization Complete'. The window then disappears leaving just the Solution Accelerators background.