The .ad file extension is related to the After Dark software and used for its screen saver files.
AD file extension - After Dark screen saver file
What is ad file? How to open ad files?
File type specification:
The AD file extension is associated with the After Dark a computer screen savers software for Apple Macintosh and Microsoft Windows developed by Berkeley Systems. The .ad file contains screen saver.
The After Dark is obsolete product without support from developer.