Just an update
In same machine, I've installed: sudo apt-get install linux-headers-generic-lts-trusty linux-image-generic-lts-trusty
After that, I've rebooted with that kernel:
3.13.0-62-generic
Once rebooted, VirtualBox works OK, and all VMs works as expected.
If I reboot again with vivid kernel, VirtualBox stops working.
So, seems like a problem with 3.19.0 kernel.
Just an update
In same machine, I've installed: generic- lts-trusty linux-image- generic- lts-trusty
sudo apt-get install linux-headers-
After that, I've rebooted with that kernel:
3.13.0-62-generic
Once rebooted, VirtualBox works OK, and all VMs works as expected.
If I reboot again with vivid kernel, VirtualBox stops working.
So, seems like a problem with 3.19.0 kernel.