I had a similar problem with my car stereo after upgrading the os on my phone. I was pfutzing around in the car stereo settings and found an option marked controller. After selecting it, I found one option under controller said ipod. I selected it and the phone works fine now. I know there are a bunch of cracks and other tricks, but try going through your car stereo's options and make sure you can't re-enable your ipod control. Worked good for me. My car stereo is a Panasonic PB6100BT, but really, check your stereo settings.