where useful in that they convinced me that reinstalling the OS is
the simplest remedy for the problems.
You're welcome. But this last sentence is pretty sad because normally,
issues like yours do not require windows-style operation. For your info,
I have not reinstalled my Debian system for the last 15 years.
Reinstalling is a solution but what if in ten days the same issue arises
again? You'll ask the same questions and won't have learned much…
One of the power of GNU/Linux is that you can learn and fix problems.