Evidently, Windows is detecting that the NEC multimedia keyboard is connected to your computer. If it isn't, it must be detecting a different device as being the NEC multimedia keyboard. Maybe the problem is that your keyboard or something else is not properly installed or identified.
Removing it from the registry or the startup menu is not going to accomplish anything. You can look in the Devices list and see what is there (it is located in the Control Panel - System - Hardware tab - Device Manager. Check to see if the keyboard is properly identified and check items with yellow exclamation marks.