Sounds similar to my problem. In January 2010, while undeer certified car warranty, BMW replaced my front outer axle boots, because the boots had leaked all grease and axle was running dry. In December, I was getting rumble strip noise, and at lower speeds, car was vibrating. After warranty expired, they stated the rf CV shaft (axle) was damaged due to my driving habits (81,000 miles of easy commuting)probably caused it. I got stuck with the $800 bill for the rf axle replacement. Now I am worried about the left one. Not sure if this could happen on other side. The car runs OK now, but the question mark is still there. I feel BMW shafted me. I plan on reporting this to the appropriate fed agency. I feel ythat the boots are defective, and maybe the axle.