Virtualbox Windows 10 Guest installation is freezing up in 14.04

Although this question is quite close to being off-topic here ...

Install VirtualBox 5.0 which has improved Windows 10 support.

Remove the old VirtualBox version :

sudo apt-get purge "^virtualbox-.*"  

Update the software repositories :

sudo apt-get update

Download and register the ORACLE public key:

wget -q -O - https://www.virtualbox.org/download/oracle_vbox.asc | sudo apt-key add -  

Add the ORACLE VirtualBox repository :

echo "deb http://download.virtualbox.org/virtualbox/debian trusty contrib" | sudo tee /etc/apt/sources.list.d/oracle-vbox.list

Update the software repositories again :

sudo apt-get update

Install ORACLE VirtualBox 5.0 :

sudo apt-get install dkms virtualbox-5.0  

Download the Oracle VM VirtualBox Extension Pack and install them by opening the Preferences.

To avoid any problems - it is recommended to restart the Ubuntu system before using VirtualBox.

Note for other users reading this answer, in case they use another Ubuntu edition as 14.04 :

You have to replace trusty with the Ubuntu edition you are using when adding the repository !

As of Ubuntu 16.04 the ORACLE public key to download and register has changed :

oracle_vbox.asc has to be replaced with oracle_vbox_2016.asc !