Rf Communication Trouble On Leonardo

hi ,

im having trouble working with rf communication on arduino leonardo i upload the code posted below which works perfectly on both my uno and mega btw and the whole device freezes … when using the 1.0.5 ide the rx led stays on and i have an unknown device in the usb section of my device manager and when im working with the 1.5 ide there are no serial port for the lenoardo in the device manager but the rx is off and the unknown device is gone … im using the virtualwire library … can anyone help me out

code :

// Receiver Code (as the code is very short i post direct here, its adapted from Mike McCauleys pdf file above)

// RF Link using VirtualWire to receive messages
// simplex (one-way) receiver with a 315MHz RF Link Receiver module
// rx pin 23 on mega

#include <VirtualWire.h> // you must download and install the VirtualWire.h to your hardware/libraries folder

unsigned long time;
void setup()
{
Serial.begin(9600);

// Initialise the IO and ISR
vw_set_ptt_inverted(true); // Required for RX Link Module
vw_setup(9000); // Bits per sec
vw_set_rx_pin(7); // We will be receiving on pin 23 (Mega) ie the RX pin from the module connects to this pin.
vw_rx_start(); // Start the receiver
}

void loop()
{
uint8_t buf[VW_MAX_MESSAGE_LEN];
uint8_t buflen = VW_MAX_MESSAGE_LEN;

if (vw_get_message(buf, &buflen)) // check to see if anything has been received
{

int i=buf[1]-1;
char a =buf[0];
String l= String(a) + String(i);
// Message with a good checksum received.

Serial.println(millis()-time);
time=millis();

}

}