UPDATE 2008-12-17: See detailed instructions in the comments.
Since I haven’t found any discussion of this on the web I’ll document my experience and see what web searches bring people to this post!
By way of background, I have two external hard disks that are used for backups, one at work and one at home. When I get home or to work I open the Time Machine control panel and change the backup destination to the appropriate external drive. The system then updates the backup.
Yesterday I let the Mac OS apply the Leopard 10.5.6 update to my MacBook Pro as part of the shutdown. When I next reconnected to a backup disk and attempted to change the configuration, I got the following error:
You do not have appropriate access privileges to save file “.001b63b6df97″ in folder “Backup – Work”.
To view or change access privileges, select the item in Finder and choose File > Get Info.
I launched a Terminal and navigated to the backup volume. Sure enough, in the root of the volume
-r——– 1 root staff 16 Sep 22 09:37 .001b63b6df97