This section of the forum is intended for reporting possible bugs with Filemaker Pro.
Unless this file kicks in automatically when you open the file, you should be able to open the file and then use Manage Scripts (may have a different name in 8.5), to list all the scripts defined in the file--not just those for the current layout. You should then be able to open the script and edit it to fix the problem.
If the script does launch automatically when the file is opened, you may be able to exit out of it by pressing Esc on windows or command period on mac.
FileMaker Advanced can be very useful when solving such script issues as you can enable the script debugger before opening the file, open it and then any script that starts up will appear in the script debugger window where you can cancel the script or even click a button to open it up to edit it.