Error installing Virtualbox on Ubuntu 14.04.3

[^rooker]

Installing VirtualBox on Ubuntu Trusty server 14.04.3 (64bit LTS) out of default repositories, gives me the following error:

Setting up libxmu6:amd64 (2:1.1.1-1) ...
Setting up virtualbox (4.3.10-dfsg-1ubuntu5) ...
* Stopping VirtualBox kernel modules
...done.
* Starting VirtualBox kernel modules
* No suitable module for running kernel found
...fail!
invoke-rc.d: initscript virtualbox, action "restart" failed.
Processing triggers for ureadahead (0.100.0-16) ...
Setting up virtualbox-dkms (4.3.10-dfsg-1ubuntu5) ...
Loading new virtualbox-4.3.10 DKMS files...
First Installation: checking all kernels...
Building only for 3.19.0-25-generic
Building initial module for 3.19.0-25-generic
Error! Bad return status for module build on kernel: 3.19.0-25-generic (x86_64)
Consult /var/lib/dkms/virtualbox/4.3.10/build/make.log for more information.
* Stopping VirtualBox kernel modules
...done.
* Starting VirtualBox kernel modules
* No suitable module for running kernel found
...fail!
invoke-rc.d: initscript virtualbox, action "restart" failed.
Setting up libqtgui4:amd64 (4:4.8.5+git192-g085f851+dfsg-2ubuntu4.1) ...
Setting up libqt4-declarative:amd64 (4:4.8.5+git192-g085f851+dfsg-2ubuntu4.1) ...
Setting up libqt4-opengl:amd64 (4:4.8.5+git192-g085f851+dfsg-2ubuntu4.1) ...
Setting up virtualbox-qt (4.3.10-dfsg-1ubuntu5) ...
Processing triggers for libc-bin (2.19-0ubuntu6.6) ...

*sigh*...

Strange things found:
This was a fresh install. The only thing done was "apt-get upgrade" after install.
After reboot, for some yet unknown reason the kernel it runs on is:

linux 3.19.0-25

Although the current officially latest kernel for Ubuntu 14.04.3 (Trusty) should be:

linux 3.13.0-66

The 3.19.0-25 is available in linux-image-virtual-lts-vivid.
But I don't know (yet) why this image is installed...

To be continued...