OpengGL not working with any application

[Demian]

Hello

None of my games or apps (eg: Photoshop CS4, Counter Strike) recognize hardware support for OpenGL.
I'm running Windows XP Pro SP3 with a Geforce 9800 GT, latest Nvidia drivers installed (191.07).

OpenGL Extensions Viewer says "Your current video configuration DOES NOT support hardware accelerated OpenGL".

But... there's no reasonable reason that it doesn't !

I've searched the net for 4 hours now, found a few people with the problem, but no one with a solution.

Any help greatly appreciated !

[ZbuffeR]

When nvidia drivers are installed, all cases I heard of were solved by one of these :
- check no custom opengl32.dll is present in the .exe directory (rare nowadays)
- check hardware acceleration slider is at the maximum
- use only 1 screen (if you had dual screen)
- MOST LIKELY: completely uninstall nvidia driver (and other video drivers such as ATi/AMD, etc, there are tools to help), reboot, then reinstall it with administrator privileges and anti-virus disabled, then reboot again.
- kill/uninstall some random app wich was running in background and crippling GL (some version of mathlab could do this in the past)
- reinstall from scratch OS + video drivers (extreme but solved some cases)
- change the video card because the hardware was actually broken

[Demian]

Thanks a lot for this complete answer !
I'll probably have to take the extreme option, since I had already tried the other more reasonable ones to no avail.