If you use optimus technology with a nvidia chip make sure you right click on your game, and go into the "run with graphics processor" then choose "change default..." Once in this menu browse for the laucher, and .exe file for Diablo3beta, and choose "Integrated Graphics" for both files. This is all done on Windows 7 by the way. Very excited that I have a chance to play beta if I get an invite now.
If you have a laptop with Optimus Tecnology with a Nvidia 540M (that's mine) or any other please post if this works, and what type you have. Also make sure you go into your setting, and give it all the administrator rights.
PS - Move to beta feedback/bugs