CAD tip # 3236:

Go to Windows System settings of your computer and in the Environment variables, make sure that the PATH variable contains the folder name C:\Program Files\Common Files\Autodesk Shared (without the backslash at the end, you can remove it using the Edit button); maybe also stored in Program Files (x86).

If the file is really missing, you have to reinstall or repair your AutoCAD installation.

To set Windows environment variables, right-click on the 'My Computer' icon, select 'Properties'. In the 'System Properties' dialog, go to the 'Advanced' tab and click the 'Environment variables' button. You can modify the User- (for you) or System- (for all) variables.