iBook G4 firewire not working after Security Update

Hi everyone.

I have a dual 2Ghz G5 PPC and and iBook 1.33 G4, both running 10.4.11, the iBook with the latest security update, the G5 does not.

I am using an external FW drive "DVico" containing a 60GB HD. The enclosure is FW powered.

This enclosure with the same cable works perfect on the G5, I attach it to the iBook and it does not mount, however the drive is being powered by the firewire port because I can hear it spin up.

1) Have tried nvram/PMU reset with no results.
2) Got hold of an Apple Service Diagnostics (ASD) Disk (v2.5.7) and ran the firewire port test in loop mode (x 1000), it passes every time.
3) The System Profiler states "Maximum Speed: Up to 400 Mb/sec."
4) It does not appear in Disk Utility, I have heard sometimes OSX does not like to mount a drive for wahtever reason but it can be seen in Disk Util.
5) Then I attached a separate external enclosure with external PSU and a different cable, no joy!
6) It does not work with iSight, but the camera is getting power.

Is there a possibility that the latest Security Update killed my firewire port? It would not be good to install the Security update on the G5 in case it had. I would be SNAFUed if the G5 could not mount my 2 TBs of data hanging off the firewire port. Is it probable that the ASD did not detect the port as being defective? If it was the security update, can it be removed?

Many thanks,
CSR