How do I fix my installation of ATI Catalyst Video Driver in 12.04 LTS?

My graphic card is a Mobility Radeon HD 4200 Series.
I tried the 2 answers from What is the correct way to install ATI Catalyst Video Drivers (fglrx) ?

But unfortunately, it does not work for my Mobility Radeon HD 4200

_{Note
when I raised this question in May 2012, there was only 2 answers to Stephen Myall's question, since then many answers have been added to his post, it is the master post about this subject}

Update of the solution (18 nov 2012)

because new drivers are available in ATI website.
Solution in 12.04LTS is then:

---

Uninstall ATI driver

$ sudo sh /usr/share/ati/fglrx-uninstall.sh --force   (if file is existing)
$ sudo apt-get remove --purge fglrx fglrx_* fglrx-amdcccle* fglrx-dev*

Install free driver

$ sudo rm /etc/X11/xorg.conf
$ sudo apt-get install --reinstall libgl1-mesa-glx:i386 libgl1-mesa-dri:i386 xserver-xorg-core
$ sudo dpkg-reconfigure xserver-xorg

Reboot

$ sudo reboot

Download ATI driver

Check what is your Graphic Card: lspci -v | grep -A 12 VGA

Download the appropriate driver for your machine here from the AMD/ATI Website .
File should be something like amd-driver-installer-12.6-legacy-x86.x86_64.run

_{If you are looking for old driver 12.6, today (Jan 2015) it is not available anymore in AMD website. Solution is to to search it in mirror websites.}

Create a folder

$ mkdir ~/catalyst12.6/
$ cd ~/catalyst12.6/

And move your downloaded driver in it.
Unzip it if needed.

$ unzip amd-driver-installer-12.6-legacy-x86.x86_64.zip

Install ATI driver

$ sudo apt-get install build-essential cdbs dh-make dkms execstack dh-modaliases fakeroot libqtgui4

$ sudo chmod +x amd-driver-installer-12.6-legacy-x86.x86_64.run
$ sudo sh ./amd-driver-installer-12.6-legacy-x86.x86_64.run --buildpkg Ubuntu/`lsb_release -sc`
$ sudo dpkg -i fglrx*.deb
$ sudo amdconfig --initial -f

Reboot and Check if installation is successful

$ sudo reboot
$ sudo fglrxinfo

   display: :0  screen: 0
   OpenGL vendor string: Advanced Micro Devices, Inc.
   OpenGL renderer string: ATI Radeon HD 4200 Series 
   OpenGL version string: 3.3.11653 Compatibility Profile Context

It is all good, as you can see, after last reboot, fglrxinfo displays my ATI Graphic card correctly.

Thanks

I found this solution thanks to Pavel and his link

Note

I applied successfuly this solution on 3 PCs on 12.04LTS :
- one with a ATI Radeon HD 3400
- one with a ATI Radeon HD 4200
- one with a ATI Radeon HD 4350

Successfully on hybrid ATi Radeon HD 5650/Intel with driver version 12.10, Precise Pangolin 12.04.02 with configuration in BIOS select 'discrete' graphic. (Acer aspire 4745G)