Apple releases firmware updates for its devices now and again, but it seems that AirPort and Time Capsules see the most updating. Perhaps that’s because computers usually see only one update during their lives while AirPort products tend to last longer than computers. Firmware is low-level “software” that generally lives in some sort of flash memory, and controls the most basic functions of a computer or other electronic device like power flow, how various components interact, and at what speed.
In an AirPort base station or Time Capsule, the firmware also controls function of the ethernet and USB ports. A recent firmware update to the AirPort Extreme base stations rendered the AirPort Disk function unreliable. AirPort Extremes allow you to hook up an external USB hard drive that can be accessed over the network—a killer feature—but the 7.4.2 firmware is reported to bring frequent disconnections of hard drives. The only fix was to restart the base station through AirPort Utility, or by power cycling the device.
Luckily, it’s very easy to revert to earlier firmware versions using AirPort utility, found in the Utilities folder on any Mac running Leopard or Snow Leopard (Mac OS X 10.5 or 10.6). Along the left side of AirPort utility, you’ll see your base station. Click once on it, then click the Manual Setup button on the right side of the window. This will bring up the configuration options. In the Summary section, click on the word Version to show a list of previous firmware versions. You can move back one version or several, but I’d advise only to backtrack one step and only if you’re having specific issues not resolved by standard troubleshooting tactics.