Editor Splash Screen freezing

When I open a Project with Unity (2019.1.8) the splash screen opens, but thats all. The splash screen freezes and persits, until I close unity in the task manager. In the Task Manager I can see that Unity isn't answering (see attached screenshot). The same project was opened on 3 other computers without any problems, also if I open and upgrade the same project with another unity version (2019.3.6) it works totally fine. Creating a new Project with Unity 2019.1.8 is also working fine. Does anyone have an idea or a solution for this problem? I allready deleted and reinstalled Unity 2019.1.8 via Unity Hub, nothing changed.

Don't ask why I can't just use Unity 2019.3.6, as it works fine, I would prefer to do so but it's not my decision. Would be awesome if someone could help me!