Unity 3D or Gnome 3 doesn't work with Intel card (switchable graphics)

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http://askubuntu.com – I have a system with switchable graphics: an ATI Radeon HD 6770M, and an Intel HD 3000. I installed the driver from additional-drivers. The Post Release Updates one was unable to be installed, so I simply installed the other one. Everything works fine with the AMD card. The problem is when I switch to the Intel card to get more battery life, I have to use Gnome classic or Unity 2D. Unity 3D or Gnome 3 does not work. Does anyone have a solution for this? Thank you in advance. I have Ubuntu 12.04 LTS 64-bit. EDIT: I have uninstalled Unity, so my objective is to get Gnome 3 working with my (HowTos)