"Error 1931.The Windows Installer service cannot update the system file because the file is protected by Windows. You may need to update your operating system for this program to work correctly."

This error will sometimes appear on Windows XP when installing GearPlayer 3.
This means that a system file was unable to be updated during the installation because it was in use.
If this happens, click continue to proceed with the installation anyways and restart the computer after the install is complete.
The restart should then allow the file to be updated so that GearPlayer can operate on that computer.