Поиски продолжаются )
Сообщение в логе, связанное с этим:
NVRM: corruption and stability problems, and is not supported. drivers including, but not limited to, vesafb, may result in requires the use of a text-mode VGA console. Use of other console on the primary VGA device. The NVIDIA Linux graphics driver Your system is not currently configured to drive a VGA console.

Это сообщение изчезает, если прописать параметры ядра
video=vesa:off vga=normal

При этом разрешение 640х480 и обои рабочего стола Gnome под X11 на карточки GF 8600M GS с драйверами nvidia-legacy-340xx не повреждаются.
Вот что пишут сами nvidia:
The nvidia forum post by sandipt mentions:
"Our current software architecture doesn't preserve the contents of FBOs across modeswitches or power events. As a result, our implementation relies on applications re-rendering to their FBOs every frame. This is a fundamental limitation of our design that will be fixed in the future."

Basically, vesafb with the nvidia driver was never supported. It used to work,
it may still work, but that's by pure chance.

Вот почему я ставлю их для мира Linux ниже Майкрософт )