LibreOffice not starting anymore on Windows.

Hi,

i have a strange problem on 2 boxes running Windows 20H2. On the first one i got this problem a while ago and nothing helps (resetting profile, un-/reinstalling, repair installation) and now i got another one behaving similar.

Libreoffice Version is 7.1.6.2

The first one starts libreoffice programs in the background and i got them showing in the task manager, they stack up if i try to open it another time.

The second one doesn't do anything if i try to start a libreoffice program, and nothing sits in the task manager.

I can make it work if i start libreoffice in safe-mode and sticking to safe mode, but if i try any option offered in the safe mode, e.g. resetting profile and so on, it just behaves the same as before, i also deleted the profile manually, un-/re-/repair-installed libreoffice, downgraded to an older version, used another windows user profile, it always behaves the same.

How can i figure out what is going wrong on those machines, or does anyone already have a solution to that?

Thanks in advance

Juergen