Preferences files vary by name and location for each version of Photoshop. Use this document to find or re-create preferences files for Photoshop CS5.
To re-create the preferences files for Photoshop, start the application while holding down Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac OS). Then, click Yes to the message, "Delete the Adobe Photoshop Settings file?"
Important: If you re-create the preferences by deleting the Adobe Photoshop CS5 Settings file, make sure that you only delete that file. If you delete the entire settings folder, you also delete any unsaved actions or presets.
Reinstalling Photoshop does not remove the preferences file. Before reinstalling Photoshop, re-create your preferences.