This hint is for those who are attempting to reinstall Acrobat 6.0 Pro.
If you have, for some reason, deleted the Adobe PDF 6.0 folder in the /Users/Shared folder, Acrobat 6.0 Pro will present a dialog box saying that it cannot continue installation when the application icon is double-clicked.
All you need to do is to created an empty folder named Adobe PDF 6.0 in the Shared folder. Then, try launching Acrobat 6.0 Pro again. The installation will proceed and it will install all necessary components in the Adobe PDF 6.0 folder.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031105021213465