uninstalled all add-ons and then P3DV4.
I deleted all files on the C: drive that related to either add-ons or the sim.
And I deleted all sim Files and the installation folder on the installation-drive.
I did not delete things like AS2016 Weather machine or FS-Commander as they
are not intertwined with the sim.
I did not re-install Windows.
It seems that there were problems caused by either
- a failed windows update (the last creators update) that is not supported by my mainboard (ASUS)
- a BIOS Update of the mainboard
- a FSDT Live Update
which I performed in quick succession, so I do not know, when and what really started.
First, the FSDT Airports did not show up anymore, then the installation of the CRJ failed
and then, yesterday, one PMDG plane was not registered anymore and could not be registered or started.
That's when I decided to do a clean install.
On the machine is only the Simulator, basic Windows components (including Windows Defender) and Firefox installed, so interference with other
programs is not likely.