ubuntu – Problems running Virtualbox

I’m currently having issues running Virtualbox on Ubuntu 22.04.3 LTS.
At first I didn’t pay attention to the following issues during the installation (I removed the hostname):

Nov 28 11:50:48 <hostname> systemd[1]: virtualbox.service: Failed with result 'exit-code'.
Nov 28 11:50:48 <hostname> systemd[1]: Failed to start LSB: VirtualBox Linux kernel module.

The Google answers I found for that error messages didn’t help, unfortunately.
I still tried to run Virtualbox, which ends up in an error message (First sentence: Couldn’t start/open session for VM WinSrv2019):

Für die virtuelle Maschine WinSrv2019 konnte keine neue Sitzung eröffnet werden.
The virtual machine 'WinSrv2019' has terminated unexpectedly during startup with exit code 1 (0x1).
Fehlercode: NS_ERROR_FAILURE (0x80004005)omponente: MachineWrap
Interface: IMachine {85632c68-b5bb-4316-a900-5eb28d3413df}

After that, a second error message pops up saying “Kernel driver not installed (rc=-1908)” and to run ‘modprobe vboxdrv’ as root which returns following error:

modprobe: ERROR: could not insert 'vboxdrv': Key was rejected by service

FYI: Even with or without installed Virtualbox (after the initial installation) I get an error message (something like): “A system application had a problem”, after every reboot. But I can fix that by checking “ls -la /var/crash/” and then removing the entries via “sudo rm /var/crash/*”.