The add-in is still on the disabled list and whenever I want to check the box it says something like “The add-ins from HKEY_LOCAL MACHINE cannot be changed.”

Vista Ultimate x64
Office 2007 Enterprise
Adobe Acrobat 8 Pro

Adobe PDF Printer Missing Fix - Adobe Acrobat 8.1 - Vista
Gnavicks - 05:29pm Jul 24, 2007 Pacific
Adobe PDF Printer Missing Fix - Adobe Acrobat 8.1 - Vista

1. Type “C:\Windows\inf” into the search box on the start menu.
2. Locate the INFCACHE.1 file and right-click it and select Properties.
3. On the INFCACHE.1 Properties window tab to the “Security” tab and click the “Edit” button to change permissions on this file.
4. On the Permissions for INFCACHE.1 window click the “Add” button.
5. On the Select Users or Groups window click the “Advanced” button.
6. A new Select Users or Groups window will open and then click the “Find Now” button.
7. The search results are sorted alphabetically; locate the username you logon to Windows with and then double-click.
8. Under the “Enter the objects names to select…” you should see something like this YOURCOMPUTERNAME\Yourusername
9. Now click the OK button.
10. You will now return to the Permissions for INFCACHE.1 window.
11. Under the Permissions for Yourusername you need to tick “Full Control” under the Allow column. Click the “Apply” button and then the “OK” button.
12. You will be prompted with a “Windows Security” window, just click the “Yes” button and continue.
13. Delete the INFCACHE.1 file.
14. Restart your computer.
15. Open Adobe Acrobat 8.1
16. Locate the “Help” menu item and click “Repair Acrobat Installation”
17. Restart if requested to do so.

This fix worked on Windows Vista Business Edition (32-Bit).