Hi, can you please provide more details? (sorry for the late answer)
>When I start an VM, I am getting the message mentioned in the subject, but also >another error with ><quote> >Für die virtuelle Maschine pfSense konnte keine neue Sitzung eröffnet werden. > >The virtual machine 'pfSense' has terminated unexpectedly during startup with >exit code 1 (0x1). > >Fehlercode:NS_ERROR_FAILURE (0x80004005) >Komponente:MachineWrap >Interface:IMachine {b2547866-a0a1-4391-8b86-6952d82efaa0} ></quote> >... :( > > >Trying to find a solution in the web, trying to reinstall all >installed>virtualbox packages (virtualbox, virtualbox-guest-dkms, >virtualbox-guest-utils, >virtualbox-guest-x11, virtualbox-guest-additions-iso and virtualbox-qt), >changing all /dev/vbox files with "chmod 666 /dev/vbox*" (a tip I found >somewhere in the web) did not change anything ... :( please remove all the virtualbox-guest-utils virtualbox-guest-dkms and virtualbox-guest-x11 (they are needed inside the VM, not outside) and do apt-get install --reinstall virtualbox virtualbox-dkms and post the result here (or a simple dpkg-reconfigure virtualbox-dkms) after that an lsmod |grep vbox and find /lib/modules/ -name "*vbox*.ko*" -exec modinfo "{}" \; this will give me a clue about the kernel module build, and the reason for having a bad /dev/vbox* device also ls /dev/vboxdrv -l and last thing: dpkg-query -l |grep virtualbox thanks, G.