Ok so in english your saying...I should uninstall Direct X, install DX9. Then reinstall my video driver?
There is a small file "dxwebsetup.exe" available from Micro$oft downloads.
It will repair and update your DirectX to the latest.
That first, then the latest nVidia 260.99 package, and you've done all you can...
Also:
Check your nVidia Control Panel before attempting to run the game.
Set to High Performance. No forced AA, AF or vsync.
Select vsync off, from the game menu.
Try to get your monitor identified by Windows, mine is identified by name.
(The dxdiag posted had 'unknown monitor' and 'unknown native mode' listed.)
Good luck,
Regards