Quoted from http://www.adobe.com/support/contact/cs4clean.html:

Adobe – Adobe CS4 Clean Script

Adobe CS4 Clean Script

The Adobe CS4 Clean Script will help resolve installation problems experienced by users of Adobe Creative Suite 4 software. The script can clean up install records for any beta and pre-release installations of Adobe Creative Suite 4 or Point Products. The Adobe CS4 Clean Script is designed to not interfere with existing Creative Suite 3 products, but it allows you to specify if you wish to remove them as well.

1. Back-up all data stored in Adobe product directories prior to using the CS4Clean Script, including custom plug-ins, preference files or profiles you have installed.
2. Uninstall the Adobe Creative Suite 4 products prior to using the CS4 Clean Script.
   • On Windows XP, uninstall via Add/Remove Programs in the Control Panel.
   • On Windows Vista, in the Programs And Features section of the Control Panel, select Uninstall a Program.
   • On Macintosh, the uninstaller is in Applications/Utilities/Adobe Installers.
3. Download the appropriate file from below.
4. Unzip the download, or mount the .dmg file (Mac). The download includes the script as well as a ReadMe file with detailed instructions.
   • On Windows, right click CS4InstallerDatabaseUtility.exe and select Run As Administrator.
     Note: When the Run As Administrator option is not available double click on CS4InstallerDatabaseUtility.exe.
   • On Macintosh, double click Adobe Creative Suite Cleanup.
5. Follow the on-screen prompt to complete the script. Once the script completes press Enter or Quit (Mac) to exit.
6. Restart your system.
7. Now you can proceed with your installation of the shipping version of Creative Suite 4.

Download

It is important you read and carefully follow the ReadMe instructions included with the download.

English/Japanese

• Download the Adobe CS4 Clean Script for Windows (ZIP, 4.6 MB)
• Download the Adobe CS4 Clean Script for Macintosh (DMG, 588 KB)