Apple has released an update for Mac OS 9 - Hard Drive Update 1.
Hard Drive Update 1: "Improves the longevity of some hard drives shipped in certain Power Mac G4 computers," Apple says.
It is for systems running Mac OS 9.1 on the following models: Power Mac G4 Cube, Power Mac G4 (AGP Graphics), Power Mac G4 (Digital Audio), Power Mac G4 (Gigabit Ethernet), Power Mac G4 (Quicksilver).
Not all Macs will require the update, Apple warns: "Most drives do not need this update. You can check the drives in your computer by running this update. If the update is needed, a message will appear which says that "one or more hard drives in your system need updated firmware." You will be allowed to quit (cancel) at this point in order to complete backup prior to the actual update.
Apple warns users to back-up data held on the drive before they apply the update.