Running Windows Vista, or 7, and not version 16.5? Close DE CIS and start the program again with the right-click>Run as Administrator option, open a design and create a netlist to get the required components registered. Note: for some Enterprise Editions, turn off User Account Control for the user accounts, reboot required. Then start DE CIS, open a project and create a netlist. If required, UAC can be restored after the netlist is working.