"Moving items into place" freeze on Software Update, Apple .dmg's

Mid summer went to update Aperture, got to the "Moving items into place" and just stayed there. Then, when all the update for Mountain Lion came out, same thing with iPhoto's update. Tryed the .dmg's, same thing. Many hours on phone, established a second administrator account, checked out the HD's status, still the same. Booting into Safe Boot allowed the installation(s) to complete, but not a great solution. I thought that this was my machine, but my wife's near identical 13" MBPro did the same thing yesterday when she tried via Software Update. Again, Safe Boot allowed the installations to complete.

One thing, it seems only to happen on Apple's graphics or "lifestyle" apps ... iWork went OK, but Aperture, iPhoto, iMovie are the ones that seem to hang. Maybe that can help diagnose this. For what it's worth, I think the problem is something gone amiss in Apple's installers for some of these programs.

13" MBPro, OS X 10.7.4