I received this Message from Dulce to NOT upgrade to the new QuickTime.

A quick heads up. Please do not update your Macs to OS 10.5.6 which was released Dec 15th. The previous version 10.5.5 and earlier are fine.

Please also pass this along to the relevant people in your organization and customer.

There seems to be a crop of new issues with this new release and will render the RAID not detected and not mountable (the data is still okay on the RAID), our engineering team is working on the solutions with Apple.

This issue affects PCI-express RAID based products on Mac Pros; PRO DQ, PRO RX, Quad, Duo Quad.

We have also seen on 2007 Mac Pros where the PCI-express configuration (Expansion Slot Utility) setting does not 'stick', it reverts to x8, x1, x1, x16 speeds always. So any PCI-express cards installed are affected also.

The only way at this time is to use 10.5.5 or earlier, if already updated to 10.5.6 a restore to a point prior to update from your backup or unfortunately if no backup a reinstall from DVD is required to go back to an earlier version.

More to come as we have more information.