Solving Unity Desktop Freeze After Login

After I installed Ubuntu 14.04 as a guest using Virtaulbox on Windows 7 there was an issue. The Unity desktop freezes after I login. To resolve this issue you need to install guest addition iso as following:

$ sudo apt-get install virtualbox-guest-additions-iso

 one more step you may need to fix display resolution problem is to install virtualbox guest dkms.

$ sudo apt-get install virtualbox-guest-dkms

Then you need to reboot

 ref:
1 - http://www.juanrubio.me/2014/02/ubuntu-trusty-virtualbox-guest-additions/ 
2- http://askubuntu.com/questions/452979/resolution-doesnt-change-when-resizing-virtualbox-window