Apple's accused of giving some Mac owners a Judas Kiss with the release of Mac OS X 10.4.11.

Reports from sources indicate Apple may have shipped the software update with a bug that has a rendered some - but not all - systems inoperable.

The problem appears to affect older Macs set-up with a Boot Camp partition for running Windows. When running Software Update on some Macs,reports indicate users encounter an error message telling them: "Software Update has encountered an unexpected issue, you must restart."

When restarting, users find their Mac partition hangs on the blue screen and they are unable to restart their Macs from either the OS X partition, or the Windows partition. Sources claim that Apple support staff suggest the only solution is to erase the entire drive and all data in order to resolve the problem.

This threatens users with a double whammy - the loss of their existing data and the loss of the Boot Camp partition, because that software is no longer available for Tiger users to download and install.

It is not known how consistent a problem this is, nor how many users have been affected.

A discussion forum thread concerning this topic hosted on Apple's support website has already generated 24 replies and 440 views, with another related topic - "How can I remove 10.4.11 update" generating its own clutch of 240 views.

The flaw is known to have affected an analyst firm's former Apple analyst, who writes: "It is evidence (in my opinion) of very sloppy software release. To crash a system on a known problem with Boot Camp is 100 per cent totally unacceptable. People (like me) have just too much stuff on their systems to be having to start over with hard disk reformat."