Could not leave well enough alone...My Moto 551 works perfectly with my '05 X, but being a glutton for punishment, I just bought an unlocked Treo 650. Amazing phone/PDA, but , goes bat$hit when connecting to the ULF in the X5. It pairs, then the Treo goes into an endless loop of soft resets. I hate to send it back, because of all of its features, but I also hate to lose Bluetooth in the X. Anyone had any luck making the 650 work?