If you enable Personal File Sharing on your computer and other users log in to copy applications to your computer, it's possible that an application in your Drop Box folder won't open. This happens when a user connected as "guest" copies an actual application file to your computer.
For a guest to leave you a working application, he or she should make an archive of the application and then copy the archive to your Drop Box instead of the original application.
To create an archive of any file or application, select it in the Finder, Control-click it, and choose Create Archive of "File_Name" from the shortcut menu. When you receive an archived application, just double-click it in the Finder to unarchive it, then double-click the resulting file to open the application.
This document will be updated as more information becomes available.
A note about copyright
Mac OS X software may be used to reproduce materials. It is licensed to you only for reproduction of non-copyrighted materials, materials in which you own the copyright, or materials you are authorized or legally permitted to reproduce. If you are uncertain about your right to copy any material, you should contact your legal advisor.