Comment 5 for bug 147303

What's going on is, bulletproof-X mode attempts to use Vesa for booting, and generates an xorg.conf with what it thinks are safe defaults.

Can you please attach your /etc/X11/xorg.conf.failsafe, so we can compare the settings it's using with what actually works? Perhaps the detected BusID is wrong, or it's missing an option necessary to make it work correctly.

Also, please attach the output from lspci -vvnn.

I suspect it's probably irrelevant, but can you also indicate if you have -fglrx installed, or if you only use -ati?