|"Upon realizing installer was not working I downloaded and installed (at least I think) installer 4.5.6001.22162 via a "hotfix"|
That shows up when I do the "msiexec" entry from the command prompt. "
If it shows the version no problem when you type msiexec, Windows 4.5 was probably installed correctly, but it may NOT have been enabled correctly.
Go to Control Panel - Classic view - Administrative Tools - Services
(or type services.msc in the Start Search box, press Enter)
Scroll down to the Windows Installer entry.
Double click on it.
Startup type should be Automatic
Service status should be Stopped (when Windows Installer is not running).
If either of those settings are otherwise, change them, then click on OK at the bottom of the Windows Installer Properties window, Restart Windows, then try installing what would not install because of the Windows Installer error before.
Other possibilities. Windows Installer 4.5 may not have installed 100% properly because of this....
NOTE that sometimes the resident module(s) of anti-malware programs - a part that runs all the time scanning for suspicious activity - will interfere with the proper installation of third party software, or major Microsoft updates that cannot be installed automatically by Automatic Update, the software will not install properly, and you may get no indication of that at all while installing the software.
To avoid that possibilty, you should always DISABLE the resident module(s) of anti-malware programs, BEFORE you install third party software (software other than most Microsoft Updates, etc., that did not come with Windows ), especially when it's a major or complicated software package.
E.g. if you are using the free or paid version of AVG, you should disable the Resident Shield in AVG's 's settings in Windows (in AVG 2012 that's done under the title AntiVirus).
If you don't know how to do that, tell us which anti-malware software you are using.
When you are sure the software has installed correctly, re-enable the resident module(s).
How to disable your security applications
In that case, disable your anti-malware resident module(s) from running, un-install Windows Installer 4.5 in Control Panel - Classic view - Programs and Features - Restart the computer, install Windows Installer 4.5 again, Restart your computer again, then try installing what would not install because of the Windows Installer error before.
When you're sure the Windows Installer and the programs you have installed are working properly, THEN re-enable your anti-malware software's resident module(s).
"The other item you are "dead on" about is the updates. Looking at the history I see that most updates succeeded on 6/21....then later THAT DAY seems like when failures began. By 6/23 most updates had failed."
I don't know for sure, but I would think EVERYTHING you tried to install after when Windows Installer stopped working correctly would have failed to install. However, most installation software uses a Windows Installer software package, but not all of it.