Tuaw points us to a support note released by Apple aimed at addressing various issues some users were experiencing while upgrading to Mac OS X Leopard 10.5.6.
The support note explains that the issues were being caused by a “partially downloaded software update.”
When attempting to update software using Software Update in Mac OS X 10.5, the update process may stop responding while “Configuring installation” is visible in the update window.
This can occur if Software Update attempts to install an update that was only partially downloaded.
Some persistent issues still remain with Mail, mounting network volumes, and minor inconsistencies with Safari. If you haven’t upgraded already, make sure and back up your data first. You can never be too safe.