GSM Module V3 shuts down after network registration

Hello,

I'm having a lot of trouble using the GSM module (V3)..
I've tried different SIMs from different carriers, but the module stops communicating (STAT & NET lights turn off) after it registers to the network..

I've used the default sketch to communicate over serial:
[code]
void setup()
{
//Init the driver pins for GSM function
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
//Output GSM Timing
digitalWrite(5,HIGH);
delay(1500);
digitalWrite(5,LOW);
}
void loop()
{
digitalWrite(3,HIGH);//disable GSM TX?RX
digitalWrite(4,HIGH);//disable GPS TX?RX
}
[/code]

and this is the result I get:
[code]
IIII????
Sending AT query..

AT



OK

Successful response for AT query..



+CFUN: 1



+CPIN: READY

AT+CGMM



SIMCOM_SIM908



OK

Model Number : SIMCOM_SIM908


+CREG: 2

AT+CGMI



SIMCOM_Ltd



OK

Manufacturer : SIMCOM_Ltd


+CGREG: 0



+CREG: 1,"10CC","9043"

[/code]

and then the module shuts down, no NET or STAT leds, just PWR, and I can't communicate over console..
all I can do is reset..

any ideas?