Well I did try the tricks mentionned by Amnon in the thread mentioned above.

You need to enable double buffering... essentially it creates a 2nd Graphics buffer, and makes sure that one is always completely finished before it draws to the screen. The flickering you see is the failure to synchronize the rendering between your graphics card and your display refreshing.

Thanks for your answers Jesse

Vertical refresh sync issues would manifest themselves as "tearing" visible during animation (where the bottom portion of the screen shows the current frame and the top portion shows the previous - generally the most noticeable during fast horizontal animation), rather than a "flickering". The problem you describe sounds like either a double buffering issue or perhaps a more subtle issue leading to an uninitialized/corrupt frame buffer being displayed on the screen. I would not pursue vertical sync options.

Thanks Jason too :)