Whenever i try to install the mac os 10.5.5 update, it just gets stuck on "configuring installer" during the install, and wont change. i kept it on for an entire night (about 10 hours) and still nothing happened.
Are you downloading it through the automated software update or the stand-alone installer from www.apple.com/support/downloads? If its the first one, try downloading the 601 MB combo update for 10.5.5 and run that instead.