Comment 14 for bug 385658

Second is the issue that if a card is not supported by -nv, the xserver should not attempt to boot -nv, but rather use -vesa. I've filed this issue upstream as https://bugs.freedesktop.org/show_bug.cgi?id=23045 - sub to this one if you wish; it's probably the more likely bug to get solved in time for karmic.