I recently tried older drivers. I was using 84.21 prior to that.
I was using 78.01 at the time of the screenshot in the first post.
I reinstalled the version 84.21. Now I get this in Oblivion :
Screenshot
The mouse is invisible and only this shows. There's something wrong with the card, the drivers or the motherboard.
I also tried another game called Grand Prix legends. That other game seems to work perfectly in OpenGL. In Direct3D, it's unplayable as all the menus are invisible.
EDIT : I'll install the card in another computer tomorrow. That will tell me if the problem is with the card or from my computer. My card is from MSI. I just took a look at their website. They offer a warranty of three years. If it's broken, I might be able to get it repaired or replaced. I would prefer replaced, especially if they give me a new model. It can happen.