help bluetooth
 

I am new to this site so it might be a stupid question. I have a Sony ericcsson phone W880i. I have bought a bmw m3 2005 with bluetooth fitted. The dealer paired my phone and it worked fine in the car on the way home. Now when i get in the car the phone connects to the car but after about 10 seconds it says on the phone bmw has disconnected and then it reconnects again 10 seconds later and keeps doing this over and over again. I have checked compatability with the car and it is compatible. I have fiddled with the settings on the car and on my phone but it keeps doing this. Can someone please help. Thanks :(