Oracle has released VirtualBox 4.1.8, a maintenance release of VirtualBox 4.1 which improves stability and fixes regressions. See the ChangeLog for details.
To install VirtualBox open a terminal window (press SuperKey and type terminal) and copy+paste the following lines:
echo deb http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib | sudo tee /etc/apt/sources.list.d/virtualbox.list
wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add –
sudo apt-get update
sudo apt-get install virtualbox-4.1
For some additional features like USB 2.0 support, you’ll have to install the VirtualBox Extension Pack which you can download here. Once downloaded, double click the Extension Pack and it should open with VirtualBox and you can then easily install it. If that doesn’t work for you, Open VirtualBox and go to File > Preferences and on the Extensions tab, click the “add” button on the right and browse for the VirtualBox extension pack.
To install the guest additions on Ubuntu 11.10 copy+paste the following line:
sudo apt-get install virtualbox-ose-guest-utils