My 2003 530i which has 205,000 miles on it started giving me problems 2 days ago. The steering wheel radio controls have ceased to function. The radio works, but the display will not change when the radio station is changed. Also, the fasten seat belt light, door open and engine safe mode messages have also come on intermittently. I installed a new battery about 4 months ago and have had the alternator tested since these problems began. What else could be causing these problems?