For years I've used a Microsoft Natural Ergonomic Keyboard 4000 on my M6400.  Suddenly it has stopped working.  The keyboard works on other computers.  Other USB keyboards do not work on this laptop.  My laptop has Windows 7 with latest updates and device drivers.  All other USB devices are recognized and installed.  I can remove and reinsert a USB mouse, USB hub, USB printer, and iPhone with a Lightning to USB cable.  Everything else works fine, just not the keyboard. None of the status lights come on on the keyboard.  There is no response from the OS upon removal or reinsertion of the keyboard connector.

Can anyone help?