I have trying to install the new F12 Beta on my Lenovo Thinkpad T400 Laptop and every time in different section of the installation method the screen going black and that's that.
When going trough the "basic Video driver" the installation finished OK.
This Laptop have "switchable display adapter"
* Intel Graphics Media Accelerator 4500MHD
* ATI Mobility Radeon HD 3470 (256 MB) at the same time (so called "Switchable Graphics")
As for linux does not support this H.W. feature (yet) I've disabled it (in the BIOS ) an working with only with the ATI.
I presume it is something to do with the new kernel drivers for the ATI.