Have a Go 530 model and bought a 4 gb sc hc card to put music on. Seemed to play OK for first day or two but now the FM transmitter stops working after a few minutes. Aslo bought an in car charger that outputs 2.1 amps. Sometimes get some interference coming through radio which stops when i remove the charger. Anyone got any idea if these two things are related or is there a problem with unit accepting 4 gb cards. The charger was a cheap one from ebay so it may be that it is not properly screened. Any ideas appreciated.