To whom it may concern:
System Debian wheezy, laptop.
After an kernel upgrade to 2.6.39, console dimension got wrong, (maybe 800x600 at the center of the screen) and X fails to kick in complaining that dri device is missing.
Disable rivafb (kernel option)
I think nouveau driver used to depend on rivafb, if I remember correct....
As some other thread
says, I had some trouble installing nvidia driver. For my purpose, nouveau is good enough.