Some Application Updates Fail to Recognize Windows 7

I have Windows 7 Ultimate SP1 x64. I can verify that I at least have
some variety of Windows 7 by various installed applications. These
include:
* Belarc Advisor from http://www.belarc.com/free_download.html.
* ProduKey from http://www.nirsoft.net/utils/product_cd_key_viewer.html
* Windows Update (showing an update that I have not yet installed)
* Computer (both the Properties when I right-click on the icon and the
display when I select [Help About Windows] in the open window)

However, I cannot install updates to two applications whose Web pages
indicate they are compatible with Windows 7. Both throw up error popups
claiming my Windows version is not compatible. These a
* Thunderbird 60.0 (update from 52.9.1)
* Skype 8.27.0.85 (update from 7.36.0.150)
Note: I attempted to install these from complete downloaded installer
files. I disabled my Internet connection and my anti-virus application
AFTER downloading and scanning the files.

What is going on here? Is there something I can do to make these
recognize Windows 7 on my PC? Or is the problem with the installer files?

--
David E. Ross
http://www.rossde.com

Too often, Twitter is a source of verbal vomit. Examples include Donald
Trump and Roseanne Barr.