I'm new to the forum. I must confess I'm cheap, only using the free version at this time. The reason I'm doing so is that CCleaner doesn't currently address any problems in the Registry [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ComponentBasedServicing\Packages\] that currently affect user's ability to update KB's. One of the fixes that Microsoft reccomends is to rename the C:\Windows\SoftwareDistribution folder to SoftwareDistribution.old. What this is supposed to do is start the update process from scratch. This seems to create the new *.dat file, but does nothing concerning the registry.
However; when you look into the ComponentBasedServicing\Packages key, you find an entry called "LastError" everytime the KB update fails. It is my contention that this entry is what is causing subsequent KB fixes to install correctly. Somewhere in the update process, possibly the agent, is an API routine that gives the go-ahead to install subsequent "fixes" only after confirming that everything is OK up to this point. Package 1, in my case installed, package 1000 did not, and all subsequent packages. The link to the software distribution folder should be gone, so why doesn't the CCleaner program identify those entries and delete them as obsolete, or left over from previous installs? If what I say is true, Piriform would be flooded with people, including me, wanting to purchase a registry cleaner that fixes what Microsoft is apparently unable to fix.
Frank
