Congrats on busting your problem!!!!!
Bask a while in the warm feelings of relief ;^)
But am I right? Does Linux somehow remember previous installations so that my 3rd party category includes previous PPAs that I may have downloaded.
I can understand why this seems puzzling but I reckon this might be due to the extremely dynamic & somewhat
uncontrolled nature of Linux OS & PPA development.
Especially with automatically loaded updates, you cannot be sure that exactly the same runtime versions of all OS libraries & all PPAs
are installed from one day to the next.
This can mean that if you make a new install of a specific Linux version, which you previously installed (say) 6 months ago, you
do not end up with identical systems. New linux drivers/libraries and new PPAs may have appeared in the meantime & these will
be installed instead of the version you installed 6 months ago.
The ONLY way to be absolutely sure that you have an identical system to what you originally had is by restoring a disk image.
New updates are not always better & (regardless of the OS) I always prefer to manually select updates & ONLY update stuff that
is broken (If it aint broken then dont fx it).....
TIP: Buy a new hard drive, mirror your system to this drive and always test updates on this drive before mashing up your