I bought and installed the Ultra Engine again, this time as a standalone version (not the Steam version). I don't know why, but now both versions are working. Both the Steam version and the standalone version open again under Beta 0.98e. The only problem now is that when I activate tessellation, and i build a terrain the FPS drops to 10 ( 512x512) in the client 3D view. ( 64x64 fps 39) So, at the moment, I can only work with tessellation turned off. Projects are up to date in the project manager.
But for the moment i am happy to work again at my project.
burgelkat's post in Project won't load was marked as the answer