This behavior has to do with the way the file is marked as to what type of file it is and how Macintosh or Mac OS Easy Open handles generic file types.
For example: Apple Menu Options Preferences; this preference file is marked as being a generic "prefs" file. Double-clicking on the file will not open the Apple Menu Options control panel because Apple Menu Options does not contain information that it needs to open a generic "prefs" file.
Instead, Mac OS Easy Open will try to locate a suitable application to open the file by looking at which applications can open a generic "prefs" file. One of the options is the application "Megaphone", even though the application has nothing to do with the preference file. Although you can select Megaphone, Megaphone will be unable to open the file (there's nothing in the file that Megaphone can use). However, the default state of Mac OS Easy Open is from that point forward. If a file with the same type (in this case "prefs") is double-clicked, Megaphone (or the selected application) will open.
To clear this preference:
1. Go to the Mac OS Easy Open control panel and click on "delete preferences".
2. In the control panel window, under "Translation Choices Dialog Box", select the option "Always show dialog box."
Choosing this action will always bring up a choice, even though the file may already be mapped to an application. This will let you select a different application or click "cancel" if no appropriate application is found.
This article was published in the 27 June 1997 "Information Alley".