There are a few different reasons why you might receive an error message saying that the VirtualBox Linux kernel module failed to start. Some possible causes include:
The kernel modules are not properly set up. This can usually be resolved by running the following command:
sudo /sbin/vboxconfig
You do not have the necessary dependencies installed. Make sure that you have the linux-headers package for your current kernel version installed.
There may be a conflict with another virtualization software that you have installed on your system, such as KVM or VMware. Try disabling or uninstalling the other virtualization software and try starting VirtualBox again.
Your system may not have the necessary permissions to access the kernel modules. Try running VirtualBox as root using the following command:
sudo virtualbox
The kernel modules may be out of date. Try updating your system and then trying to start VirtualBox again.
There may be a problem with your VirtualBox installation. Try re-installing VirtualBox and see if that resolves the issue.