I have several clients for whom I provide Active Directory support and Windows Management for, one of these customers required a reinstallation of System Center Essentials, as the server we had installed it on originally was deemed to be not fit for purpose.
When we originally installed System Center Essentials, I patched the installation media as per KB 943111 with SCE2007RTMHotfixRollup.exe. I then copied the installation media and attempted to install System Center Essentials on an alternative server but the installation constantly failed, with errors that related to the issues that the HotfixRollup had addressed.
After about a week of hair pulling I started afresh and by accident I had the temp folder open when I started to install the HotfixRollup. I then discovered that whilst some of the files are replaced in the SCE installation media – some files are place in the %TEMP% folder for installation as part of the setup routine – this of course would not happen on my new server as I only copied over my installation set and not the content of my %TEMP% directory. So why the server has a two phased approach to applying a hotfix I will never know.
So the lesson learned for me here is never assume that what has happened has happened in a manner you expect from the appearance of something. I now can install SCE providing I run the Hotfix every time I need to install from media.