Comment 7 for bug 749817

<RAOF> So something's setting strangeness.
 I don't suppose a guest mode login works?
 Also, could you set the drm.debug=0x04 kernel parameter (either from the command line, or via /sys/modules/drm/parameters/debug) and reproduce, then attach dmesg and Xorg.0.log to the bug?

Attached is me booting up first with the external monitor attached over displayport, which fails, then disconnecting it and logging in successfully.