Comment 82 for bug 772207

It affects my system at work as well. Both with regular Xorg stack as well as with the edgers' repo.
I am running with the 173.x drivers which have the common "active... but not in use" problem as others have mentioned here before. Also, the standard Xorg configuration nVIDIA generates does not correctly recognizes the PCI address of the card so I had to comment that line out just to boot Ubuntu with the nVIDIA drivers (either that or deleting the xorg.conf file did the trick). GL feels very slow too although glxgears reports FPS to be above 1,000. lsmod does show "nvidia 8107272 36" BTW.
Ubuntu Classic *(with effects) does work, while Unity does not. I do not see menus and I see desktop icons appearing and disappearing very quickly. Not usable at all running Unity.

-----------------------------------------
Unity support test:
/usr/lib/nux/unity_support_test -p
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: Quadro PCI-E Series/PCI/SSE2
OpenGL version string: 2.1.2 NVIDIA 173.14.30

Not software rendered: yes
Not blacklisted: yes
GLX fbconfig: yes
GLX texture from pixmap: yes
GL npot or rect textures: yes
GL vertex program: yes
GL fragment program: yes
GL vertex buffer object: yes
GL framebuffer object: yes
GL version is 1.4+: yes

Unity supported: yes
-----------------------------------------

-----------------------------------------
dpkg -l | grep -i nvidia
ii nvidia-173 173.14.30-0ubuntu1 NVIDIA binary Xorg driver, kernel module and VDPAU library
ii nvidia-common 0.2.30 Find obsolete NVIDIA drivers
ii nvidia-settings 275.09.07-0ubuntu1~edgers~natty Tool of configuring the NVIDIA graphics driver
-----------------------------------------

-----------------------------------------
lspci |grep -i nvid
40:00.0 VGA compatible controller: nVidia Corporation NV37GL [Quadro PCI-E Series] (rev a2)
-----------------------------------------

-----------------------------------------
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 275.09.07 (buildd@charichuelo) Wed Jun 15 20:08:12 UTC 2011

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 1.0 (buildmeister@builder58) Sat Apr 16 22:49:04 PDT 2011

Section "ServerLayout"
    Identifier "Layout0"
    Screen 0 "Screen0" 0 0
    InputDevice "Keyboard0" "CoreKeyboard"
    InputDevice "Mouse0" "CorePointer"
    Option "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier "Keyboard0"
    Driver "kbd"
EndSection

Section "InputDevice"
    # generated from default
    Identifier "Mouse0"
    Driver "mouse"
    Option "Protocol" "auto"
    Option "Device" "/dev/psaux"
    Option "Emulate3Buttons" "no"
    Option "ZAxisMapping" "4 5"
EndSection

Section "Monitor"

    # HorizSync source: edid, VertRefresh source: edid
    Identifier "Monitor0"
    VendorName "Unknown"
    ModelName "Samsung SyncMaster"
    HorizSync 30.0 - 81.0
    VertRefresh 56.0 - 75.0
    Option "DPMS"
EndSection

Section "Monitor"

    # HorizSync source: edid, VertRefresh source: edid
    Identifier "Monitor1"
    VendorName "Unknown"
    ModelName "Samsung SyncMaster"
    HorizSync 30.0 - 81.0
    VertRefresh 56.0 - 75.0
    Option "DPMS"
EndSection

Section "Device"

    #BusID "PCI:40:0:0"
    Identifier "Device0"
    Driver "nvidia"
    VendorName "NVIDIA Corporation"
    BoardName "Quadro PCI-E Series"
EndSection

Section "Device"

    #BusID "PCI:40:0:0"
    Identifier "Device1"
    Driver "nvidia"
    VendorName "NVIDIA Corporation"
    BoardName "Quadro PCI-E Series"
    Screen 1
EndSection

Section "Screen"

# Removed Option "TwinView" "0"
# Removed Option "metamodes" "CRT-0: nvidia-auto-select +0+0"
    Identifier "Screen0"
    Device "Device0"
    Monitor "Monitor0"
    DefaultDepth 24
    Option "TwinView" "1"
    Option "TwinViewXineramaInfoOrder" "CRT-0"
    Option "metamodes" "CRT-0: nvidia-auto-select +0+0, CRT-1: nvidia-auto-select +0+900"
    SubSection "Display"
        Depth 24
    EndSubSection
EndSection

Section "Screen"
    Identifier "Screen1"
    Device "Device1"
    Monitor "Monitor1"
    DefaultDepth 24
    Option "TwinView" "0"
    Option "metamodes" "CRT-1: nvidia-auto-select +0+0"
    SubSection "Display"
        Depth 24
    EndSubSection
EndSection

-----------------------------------------