Apple has posted an update to AirPort Utility, the software Macs (and Windows PCs) use to control AirPort Extreme Base Stations and AirPort Express devices.
The new 5.3.3 release is available for download either through the Software Update system preference or from Apple’s Support Downloads Web page.
The update sports bug fixes, and “resolves an issue that caused the AirPort Utility to unexpectedly quit during setup,” according to Apple.