I am also experiencing this issue, running Vivid on an amd64, using the nvidia 340.76 drivers which are not as recent as the 346 drivers but are the recommended drivers for my card:
~$ sudo ubuntu-drivers devices == /sys/devices/pci0000:00/0000:00:04.0/0000:03:00.0 == modalias : pci:v000010DEd00000400sv00001682sd00002280bc03sc00i00 manual_install: True vendor : NVIDIA Corporation model : G84 [GeForce 8600 GTS] driver : nvidia-340 - distro non-free recommended driver : nvidia-304 - distro non-free driver : xserver-xorg-video-nouveau - distro free builtin driver : nvidia-304-updates - distro non-free driver : nvidia-340-updates - distro non-free
I am also experiencing this issue, running Vivid on an amd64, using the nvidia 340.76 drivers which are not as recent as the 346 drivers but are the recommended drivers for my card:
~$ sudo ubuntu-drivers devices pci0000: 00/0000: 00:04.0/ 0000:03: 00.0 == 0000400sv000016 82sd00002280bc0 3sc00i00 xorg-video- nouveau - distro free builtin
== /sys/devices/
modalias : pci:v000010DEd0
manual_install: True
vendor : NVIDIA Corporation
model : G84 [GeForce 8600 GTS]
driver : nvidia-340 - distro non-free recommended
driver : nvidia-304 - distro non-free
driver : xserver-
driver : nvidia-304-updates - distro non-free
driver : nvidia-340-updates - distro non-free