I try to test Webgl on my laptop.
On the first one, every thing works like a charm.

On the second one, I've got a very strange issue :
When I try webgl exemples (such as http://learningwebgl.com/lessons/lesson01/index.html and many other) with Firefox, the browser tells me that He can't initialize webgl.
When I try using Chromium, i've got a black canvas, (for exemple http://gwt-g3d.appspot.com/). It's something like everything is working but he doesn't display the 3D canvas

I've got the --enable-webgl attribute, and FF's webgl about:config set to true.

I've got an ATI radeon X1600 with the last drivers,
and OpenGL version

Am I missing something ?
Can it be possible that OpenGl ES isn't installed ?
Any help is welcome