If something goes wrong during installation, you may need to perform the following steps manually.
Add CNM path to AutoCAD:
Under the Files tab of the Tools, Options menu in AutoCAD, click the + icon next to Support File Search Path. If the CNM installation folder is not on the list of folders, click the Add... button to add it. The bottom of the list should be fine in most cases.
Add CNM menu to AutoCAD:
Use the MENULOAD command in AutoCAD to load the CNM menu. Browse for the CNM.MNU file and Load it.
TECHNICAL INFORMATION
Environmental Impact Statement:
Construction Notes Manager makes no system changes outside of AutoCAD at the time of program setup.
The setup process adds the CNM menu and the CNM program path to AutoCAD's environment.
In the course of normal usage, CNM creates registry entries and adds files to the folders containing user AutoCAD drawings.