When deploying Windows Embedded 2009 Trial Edition with sysprep you need to enter a valid runtime PID.

If you add the Trial PID you got from Microsoft into sysprep.inf, and you deploy that image, the mini-setup will display the following error message: "An unexpected error has occurred while changing your computer network configuration". Later on, after the mini-setup the Windows Embedded OS will reboot into a hang.

Solution: Retrieve the Trial runtime PID from the system (not the same as the Embedded Trial PID from Microsoft)

After building your base image (running through FBA etc.), open regedit and locate  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\WindowsEmbedded key. In here you will find the RunTimePID value. Copy that PID into sysprep.inf and it will work like a charm.