I ran into an issue with Photoshop CS5 not communicating with an older scanner. The solution was to launch PS in 32-bit mode but this needed to be changed for any user that logged in. Here’s what worked for me.

  1. On you machine, Get Info of the Photoshop app and check “Open in 32-bit mode
  2. Launch Workgroup Manager and locate your target machine.  Get to the Preferences, Details window.
  3. Click the + symbol and navigate to ~/Library/Preferences and select the com.apple.LaunchServices.plist file and make sure it’s managed “Always.”
  4. Select the newly added plist file and click the edit button.
  5. Expand the Always menu and Delete the “LSHandlers” item.
  6. Expand the remaining menu item and it should look similar to this.
  7. Hit Done and that’s it.