Blue screen Vista

Hello,i've just installed Vista Business.
Sometimes,my computer reboot automatically after a blue screen. Message
after reboot: Problem caused by Device Driver.
I have an ati radeon 9600 series with catalyst 7.1 installed. I don't know
if the problem is due to my graphic card or another hardware.

Furthermore, sometimes my screen turn off and restart with a message :
driver R300 has stopped and has successfully recovered.

Thanks for your help.

Besse Alexandre , France