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I have Ubuntu 12.04 installed on my Lenovo ThinkPad T420S.

In BIOS I have an option to select graphical card: integrated intel card or NVS 4200M (or NVIDIA Optimus which is out of scope now).

When I select integrated intel card in BIOS everything works fine. When I select nvidia system freezes after grub screen. Sometimes I get weird "ATA revalidation failed". Magic button (Alt+Fn+SysRQ+E/I/S/U/B) doesn't work.

What I have tried:

  1. Installing recent nvidia-current from x-swat ppa.
  2. Purging nvidia-current and nvidia-common
  3. Updating T420s BIOS version.
  4. Updating kernel to 3.4.7.
  5. Booting old kernel 3.2.0-18.

Nothing helps.

I don't think this is hardware issue since Windows works fine.

Any ideas?

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Subscribe to this [bug] on launchpad, I hope they will fix it. [bug]: – Andrey Dec 14 '12 at 13:59

I am having the exact same issue here. While trying to fix it, I pretty much did what you tried (upgrading to kernel 3.3 only) and even completely re-installed ubuntu. However, before the reinstall I still had a 3.0 kernel installed and booting into that, the nvidia was functional.

Conclusion: if you are willing to downgrade your kernel even further, the 3.0 kernel should still be working with the NVS 4200M...

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