Apple has released a firmware update for single processor G5 Power Macs.

The 1.5MB Power Mac G5 Firmware Updater Version 5.1.5f2 has been released in response to some reported problems following the installation of previous firmware upgrade, 5.1.5f1. Some 1.6GHz G5 Power Macs had experienced "unexpected issues", Apple reports.

"What unexpected issues? It could be a kernel panic, the loss of USB function with some keyboards or mouse tracking devices, Bluetooth USB modules that don't respond five minutes after starting up, or interrupted audio playback in iTunes. Disconnecting and reconnecting devices does not help," Apple says.

It appears that removing some or all non-Apple memory can stop these problems, and Apple advises users installing the new update to remove such RAM from their Power Mac before installation begins. Such memory can be re-installed once the operation is complete.