Symptoms of the problem. Here's a specific case. I was using DropBook to create ebooks so I could read them from my mobile phone. After the upgrade, DropBook failed to launch. When I double-clicked on the icon, it displayed the expected behavior of a launching application (the zooming action), but then nothing else happened. DropBook did not come out of the screen, nor would its icon show up on the Dock.
I did two days worth of web trawling and experimentation. Some sites recommended cleaning my application caches -- I used Onyx to do this. Some sites said to try isolating the problem by loggin in to a different account and testing (this would indicate whether the problem lay in my specific user profile only). Unfortunately, none of these solved the problem.
What finally solved the problem was an advice to just download the Combo Updater and reinstall it. Using the automated path (Click Apple icon > Software Update) would fail because the tool would only report that I had already installed the latest version.
So I went to the Apple website, downloaded the DMG file of the update, and reinstalled it. Then I waited as the Mac restarted and crossed my fingers. It turned out that this solved the problem! Whew!
- MacFixit article on the problems of 10.4.10
- On what to do when an application won't launch
- Firmware update problems