"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," the company said. "This can occur if Software Update attempts to install an update that was only partially downloaded."
To resolve the issue, Apple recommends that you quit Software Update and then navigate to the directory on your hardware where the contents of pre-installed software updates reside. To get there, select "Go to Folder" from the Go menu in the Finder and type in "/Library/Updates" without the quotes, then click Go.
When the directory opens, delete the entire contents of the folder by selecting every item and moving it to the trash. Once this is completed, you can use Software Update again to re-download and install the update.
If the hanging issue occurs while installing an update after you've logged out of your Mac OS X account (such as an update that requires you to restart), shut down your Mac by holding down the power button, then power it back on and complete the steps above.
To avoid the hanging issue going forward, Apple advises that users download and install Mac OS X 10.5.6 Update, which better checks the integrity of software update downloads before allowing installation to begin.
Apple notes that several users may have run into the hanging issue while attempting to install Mac OS X 10.5.6. The issue will only be resolved after Mac OS X 10.5.6 is successfully installed.