Created attachment 15304 [details]
The X.org-log

As I was asked on IRC by marcheu to file a bug, I'll do it. attached you'll find my Xorg.0.log and my kern.log. The xorg.conf looked like:

Section "Module"
        #Load   "GLcore"
        Load    "bitmap"
        Load    "dbe"
        Load    "ddc"
        #Load   "dri"
        Load    "extmod"
        Load    "freetype"
        Load    "glx"
        Load    "int10"
        Load    "record"
        Load    "speedo"
        #Load   "type1"
        Load    "vbe"
EndSection

Section "Device"
        Identifier      "nVidia Corporation NV10DDR [GeForce 256 DDR]"
        Driver          "nouveau"
        BusID           "PCI:1:0:0"
EndSection

First everthing was fine and X started. But after a while it started to switch back and forth between tty1 and tty7 (on which the X server is running) and I could glimpse at the things logged to kern.log. This cycle could only be broken by Ctrl+Alt+Del or a hard reset. The first time I noticed that, was with Randr12 enabled, but after I deactivated it and started again without Randr12 it lockedup also.

Please feel free to askt for any information, test or the like you'd like to have. It's very likley that I haven't provided every information you might need because it's my first bug for nouveau/randr12.