That "disappearing plugin" thing in C9

[Mod edit: please continue the discussion in the existing threads]

Long term problem that affects Windows users, thoroughly discussed here:
https://www.steinberg.net/forums/viewtopic.php?f=226&t=77564
and here:
https://www.steinberg.net/forums/viewtopic.php?f=226&t=95005
and here:
https://www.steinberg.net/forums/viewtopic.php?f=251&t=107253

Issues involve plugins disappearing or not loading, mostly on busy projects and all that happen without any notice.
Please share your experiences here, so everyone is aware.

The problem is very deep and involves Microsoft, however things got worse in C9.