After another hang up when upgrading to the current Mac OS X using ‘Software Upgrade’. In the future, I will download the Combo update from Apple and install manually. This procedure work with the 10.5.6 upgrade that actually froze unfinished when using ‘Software Upgrade’.
After downloading the Combo update (729 MB), everything went smoothly. Additionally I have always repaired permissions after any software installation. My favorite maintenance program include Onyx and MainMenu, both free.