Locking An The Keyboard but not Display

I have a network monitor running NT 4 and want to lock the leyboard to prevent unauthorised access to the machine but I also want to display the network status reports etc in real time.

Using the screen saver password does not enable me to view the screen updates. Although I could perhaps remove the keyboard I would undoubtedly need it at some stage therefore this is not an option

Is there such a utility to lock keyboard and mouse input/activity while maintaining the display refreshing