P910i iSync 2.0: never goes past "connecting..."

I used to sync my phone without any problem for months. I stopped using it for a while and synced another (V3) phone via USB. Now my P910i does not sync at all. The Bluetooth link is fine and rock solid, iSync agent is running on the phone but the iSync dialog shows "connecting" and stays this way indefinitely until I cancel manually. There is absolutely nothing in the log. I initialized the phone completely, paired and repaired to no avail. Tried to delete a few files on the Mac, made iSync forget the phone and get it back. No change. Any idea appreciated