After updating to OS X 10.3.3, Safari's contextual menu would replace "Save Image As...", "Copy (Image or Link) to Clipboard", and others with the text "localized strings not found." Also, I was unable to login to password-protected Web sites (that used .htaccess files). WebKit is affected too, and you can test this by launching the Help Viewer and control-clicking on any image.
After some online research, I discovered many others experiencing the same problem after updating to 10.3.4. The fix that worked for me was to reinstall the 10.3.4 Combo Updater and restart. Voilá! It works!

