I had to rebuild my computer due to errors. When I installed Photoshop CS5, I went to update it and it said there was an error. After many many times of trying to fix this error, I checked into this. I found that update program would download each part of the update, then when that part was 100% downloaded it would be deleted. This happened for each and every part of the update. That is why the update program error during the install. I was able to download a few of the updates from the web stie, but not all the updates were there. The parts missing are Bridge CS5 4.0.5 and Extension Manager CS5 5.0. I have been told to delete the files before running the update program. How can you delete files that have already been deleted????
An exact diagnosis of the problem would require the install logs.
Generally, though, one would simply run the cleaner tool and reinstall from scratch, then try the updates again. In fact your manual updates may have introduced blockages with shared components used across multiple apps and further updates therefore would not work, either.