Mac OS X 10.5: Software Update stops responding during "Configuring installation"

Symptoms
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.
Products Affected
Mac OS X 10.5, Mac OS X 10.5.3, Mac OS X 10.5.4, Mac OS X 10.5.1, Mac OS X 10.5.2, Mac OS X 10.5.5

Resolution
1. Quit (or if necessary, Force Quit) Software Update.
Note: If the issue occurs while installing an update after log out (such as an update that requires a restart), shut down your Mac by holding down the power button, then power it back on.
 
2. Click the Finder icon in the Dock.
3. From the Go menu choose "Go to Folder".
4. Type:  /Library/Updates
5. Click Go. The /Library/Updates folder opens.
6. Select all contents of this folder and move them to the Trash.

Once the above steps are complete, use Software Update again to re-download and install the update.