I transferred it to my Thinkpad now(running Xubuntu), there it works fine... Still don't know what the issue was or how i could have figured it out. I searched hours for a log file or a meaningful error message.

Thank you for your suggestion, if I need it on the Windows machine again, I will try that.

Meanwhile, I am pretty sure the kernel crashes instantly on startup. A bit more Information: - System is Windows 10 Pro 1903, 64 bit - Processor Core i7 3770 - 16GB System Memory

Mathematica version was a fresh Download of 12.1 Student Edition a few days ago, and it worked the first time I tried it. Now I reinstalled it, uninstalled it, deleted the Mathematica Folder in %user%\AppData\Roaming, installed it again, but nothing has changed.

It even beeps when it is showing the splash screen. When I then open a new Notebook and go t Help->Why the beep? It shows me: The kernel Local has quit (exited) during the course of an evaluation.

When I go to Edit->Preferences, it shows a popup "Formatting Notebook contents" and then keeps beeping repeatedly. The Notebook window freezes and sais "no response" in the title. I then have to kill the mathematica process via task manager.

Thanks for your attention, Björn