Thank you for the reply.
I have tried your recommendation of performing a repair using wlarp.exe. Unfortunately, it made no difference. I would have expected a repair to have produced a similar result to uninstalling and re-installing the application, and the results appear to be the same.
My suspicion is that there is something inside Windows itself that has changed that is affecting the operation of the Windows Live Mail 2012 application.
It is not the first time I have seen updates to Windows causing problems for applications. When I had a Vista PC, which I replaced with my current 8.1 desktop. I had a Roxio video editing application, a feature of which stopped working as a result of an update. However, unlike that problem, my current issue relates to two products from Microsoft.
Are there any other things I can try, other than uninstalling the updates to see if I can find which one is causing the problem?
Also thank you to ¡Firedog. I had searched for a possible thread before submitting my question but did not find your thread. Apologies for causing any problems to the community.