Having read of the security and performance issues that have been addressed in Mac OS X 10.5.5 I launched Software Update and proceeded to upgrade my MacBook from 10.5.4 to 10.5.5.

After the update and subsequent reboot my MacBook was sluggish and unresponsive. iTunes took forever to do anything and the spinning wheel was more evident than usual. I eventually managed to close iTunes and rebooted again just in case.

Big mistake!

The machine now refuses to boot up at all and shows just a flashing question mark icon. I found a relevant Apple Support article – A flashing question mark appears when you start your Mac – and followed the suggestions therein.

I booted from a Leopard DVD and loaded Disk Utility. At first it did not recognise my SATA disk, so I tried resetting the parameter RAM (PRAM). After the next reboot Disk Utility could now see my disk, but the ‘Repair Disk’ command resulted in the following error:

Verify and Repair volume “Macintosh HD”

Checking Journaled HFS Plus volume.

Invalid B-tree node size

Volume check failed.

Error: Filesystem verify or repair failed.

After a couple of attempts at this I gave up. I tried the disk in another MacBook and the same flashing question mark appears, so it looks like the disk is kaput.

Can this just be a total coincidence that a disk that has been working fine for the last year has suddenly developed a catastrophic hardware failure within minutes of updating to 10.5.5 ?