Since the first day I have my SE Arc S I have problems with the UMTS signal when it is paired via Bluetooth to my car's factory handsfree system. My car is a Renault and has the Carminat Bluetooth/navi system. - If I set the network setting to "GSM only" the signal is fine. - If I set the network setting to "UMTS only" or "UMTS (preferred)/GSM" the signal bars on my car display dissapper when the phone enters sleepmode. I only have to press on the HOME button and immediately the signal bars return. But I cannot keep pressing this button every few minutes when driving.... I was hoping that the problem would be solved with the upgrade to Android 4.0, but this hasn't helped anything Anyone else with this problem and has a solution?