It seems to be impossible to run kvm-based virtualization program and VirtualBox at the same time. There is some kind of a conflict between both programs. To make sure that a VirtualBox-based virtual machine is launched successfully, I have found a workaround. I temporarily removed all kvm modules :
root@localhost:~# lsmod |grep kvm
kvm_intel 32832 0
kvm 182683 1 kvm_intel
root@localhost:~#modprobe -r kvm_intel
WARNING: All config files need .conf: /etc/modprobe.d/kqemu, it will be ignored in a future release.
Which package does /etc/modprobe.d/kqemu file belong to ?
root@localhost:~#dpkg -S /etc/modprobe.d/kqemu
All the files in /etc/modprobe.d/ ends with .conf except kqemu. Looking at the BTS Debian, here what I found :
This package, kqemu-common, remained on my system after upgrading from Lenny to Squeeze. To avoid any error message as indicated below, you can either rename the file as follows :
root@localhost:~# mv /etc/modprobe.d/kqemu /etc/modprobe.d/kqemu.conf
or you can remove the package safely. The modules kvm and kvm_intel remain loaded and the file /etc/modprobe.d/kqemu.conf freshly renamed is still there.