radeon - Unable to switch to integrated GPU, using fglrx, Catalyst 12.6, Ubuntu 12.04

recently I installed proprietary drivers from ATI,

but I am unable to switch to integrated GPU

• using console

  
  
  

  sudo amdconfig --px-igpu
  sudo restart lightdm
  

  
  
  

  i am able to log in, but then system shows only background image

  
  
  
  

  and mouse cursor (which moves, but does not interact)




• using Catalyst Control Center

  
  
  

  system hangs and mouse moves choppy

My system configuration:

HP 4330s

Intel i5 2410M

ATI Radeon HD 6490M

Catalyst 12.6

Ubuntu 12.04