We are experiencing the same issues with the new SAMSUNG A900 and Sprint - requires turning BT off on phone and re-enabling it.
We have a new Samsung SCH-a950 from Verizon. When the car is turned on the system indicates that bluetooth has connected. We can use the screen in the car to make a call. The problem is that most of the time the voice does not switch over to the car's handsfree system; you have to talk and listen on the phone. Some of the time it works properly (i.e. the cars speaker and mic work). It seems hit and miss, it either connects fully or not, and if not, you make a call, the call goes thru annoying the called person, yet we cant talk to them. But the next time we start up the car, it might work correctly. Has anyone else experienced this behavior? The phone works fine with a bluetooth headset so it seems the phone is OK. The car works fine with another phone (Cingular/Motorola V551 always works) so it seems the car is OK. But the combination is flaky and unsuitable for prime time. I don't know what to do.