I've decided to use Thunderbird P.E. (V 18.104.22.168) from an USB-stick from now on.
The Windows version is now running and I immigrated my old Thunderbird account (plus Inbox, adresses etc.) into it.
My laptop is a macbook, I therefore also installed the MAC-Version of Thunderbird P.E.
I would like to be able to use the same account the Windows-Version uses with full access to the e-mails that are already in the Windows-version's inbox.
I'd be very thankful for any hint!