The Dow tumbled 228 points to fall below 12,000. It was the biggest drop since last October, fueled in part by reports that Saudi Arabian police fired rubber bullets to disperse about 200 Shiite protesters in the eastern town of Qatif. It seems as if any disturbance out of Saudi Arabia is enough to freak out the markets. And yet, today's fall is being viewed in some quarters as a buying opportunity. Keep in mind that tomorrow is supposed to be the "Day of Rage" in Saudi Arabia, where activists are calling for civilians to take to the streets. So there are lots of mixed messages.