Tried to install Ubuntu desktop on my Dell Inspiron 1420 but failed, finally work around it and solved the problem. All the problems encountered might be caused by my computer graphical card "NVIDIA GeForece 8400M GS", it has hardware failure before and I replaced once and still not working 100% well.

1, Install the Ubuntu desktop version "ubuntu-14.04.1-desktop-amd64.iso", the installation UI cannot display properly, cannot proceed, installation failed,

2, workaround solution, install the server version Ubuntu and then install the desktop package, successful installed the ‘ubuntu-14.04.1-server-amd64.iso‘, as it is a server version, the system was only with command line. Now install the Ubuntu desktop manager,

sudo apt-get update
sudo apt-get install gnome-core
sudo apt-get install x-window-system-core
sudo apt-get install gdm

3, realize the NVIDIA driver might be needs to upgrade.

Download from NVIDIA website, "NVIDIA-Linux-x86_64-340.32.run", executed from command line, still failed, even worse, only mouse point can be seen,

Trying to install by apt-get automatically upgrade the NVIDIA driver,  still same result,failed.

<pre name="code" class="plain">sudo apt-get --purge remove nvidia-current
sudo apt-get update
sudo apt-get -y install nvidia-current

Trying to install the NVIDIA driver by bumblebee, still same result, failed. 

sudo apt-add-repository ppa:xorg-edgers/ppa
udo apt-get update
sudo apt-get install bumblebee-nvidia nvidia-319

http://www.renewablepcs.com/about-linux/kde-gnome-or-xfce

4, the final solution I found at this link:

http://askubuntu.com/questions/413928/ubuntu-13-10-how-to-disable-nvidia-graphics-nouveau

by disable the NVIDIA graphical cards, desktop manager can work properly, at the blacklist in the /etc/odprobe.d/blacklist.conf, add one line "blacklist nouveau", and after comparing with different desktop manager, I chose KDE at last and working fine now,

sudo apt-get install kde-standard

Ubuntu desktop installation problem and solving