Problem: When Design Master files are loaded in AutoCAD 2014 or later, a File Loading – Security Concern dialog box appears that says, “An executable was found outside of the specified trusted locations.”
Solution: If you are loading Design Master for the first time, press the Load button and ignore the dialog boxes. Once the installation is complete, AutoCAD will be configured to no longer display these dialog boxes.
If these dialog boxes appear when AutoCAD is opened or a drawing is opened, run the Installation Settings command.
Ribbon: DM->Utilities-> 
->Installation Settings
Pulldown Menu: DM->Help->Installation Settings
Leave all of the settings alone and press the OK button. The command will configure AutoCAD to no longer display these dialog boxes.
Technical Background
Autodesk added the concept of Trusted Locations to AutoCAD 2014. All third-party files need to be installed from a trusted location, or the File Loading – Security Concern dialog box will be shown. Design Master configures the TRUSTEDPATHS system variable to include the install folder to eliminate these messages.
Solution for non-DM Files
If you are seeing this error message for a file that is not related to Design Master, there are two solutions:
Solution 1: Run the AutoCAD OPTIONS command. Go to the Files tab. Add the folder where the file is located to the Trusted Locations path.
Solution 2: Set the SECURELOAD system variable to 0. Using this value will load all files without any warning messages. This solution is not recommended.