FYI, I sent a reply from my iPhone several days ago, but it seems it didn't make it through. I STRONGLY RECOMMEND you stop driving the vehicle immediately. ZF specialists have advised that a cracked clutch housing can result in a catastrophic transmission failure, potentially fracturing the housing and dumping transmission fluid under your wheels and/or causing a lockup condition. This is definitely a SAFETY HAZARD. The symptoms you have are indicative of the cracked clutch housing problem on the ZF transmission. Have it towed to the nearest authorized ZF transmission service center ASAP for diagnosis. As it has been explaind to me by ZF specialists, the alloy casting that comprises the clutch housing has design flaws. Its very thin and light, and cracks. Once that happens, you get the symptoms you are feeling. Further loading can lead to housing failure. They can rebuild it for around $3K (they replace the housing with a revised design version). I'm reasonably sure that's the best you'll be able to do. Sorry to hear about your misfortune (and mine, and many others out there). If you live the US, I also recommend you report this failure to Home | National Highway Traffic Safety Administration(NHTSA) | U.S. Department of Transportation. This is a serious safety defect. If they receive enough complaints, they will open an investigation which could lead to some corrective action from BMW. Good luck, and stay safe.