If you’re running Notes in a non-standard way, ie from a shared network drive, you must have Notes open and be logged in for ndls to work. It has something to do with the way the windows registry works.
If you’re running Notes per a more standard install, ie from the default folders used when installing from a cd, then I’d suggest your registry is somehow broken. You might want to do a full uninstall (uninstall followed by deletion of all directories that Notes uses) then a full re-install.