Lpc2000

Hello
I have a problem; the folowing code, allow to trigger an interrupt via
UART0 but when the interrupt occurs one time it doesn't end. When I
send a char from PC to the LPC I receive 'A' non stop. Can someone say
me, why?

When I use the line: U0IIR_copy = U0IIR;, it ackts same. 
The code:

void UART0INT() __irq
{
	if(toggle)
	{
		IO0CLR |= 0x20000;  //clr P0.17
		toggle = 0;
	}
	else
	{
		IO0SET |= 0x20000;  //set P0.17		
		toggle = 1;
	}
	send_char_u0('A');
	//exit ISR
    //U0IIR_copy = U0IIR;
	VICVectAddr = 0x00000000; //dummy write
}

int main(void) 
{
	PLL_ON();
	LED_init();
	VPBDIV = 0x1;   
	UART0_init();                            
	IO0SET |= 0x20000;  //set P0.17
	send_string_u0(tab);
	VICIntSelect = 0x00000000;
	VICVectAddr1 = (unsigned) UART0INT;
	VICVectCntl1  = 0x26;	//UART0	
	VICIntEnable = 0x40;		//bit 6 = UART0
	U0IER   = 0x00000001;     //enable rx data available interrupt
	while(1)
	{
	  send_char_u0('B');
	}
	
	return 0;

}

P.S. Thanks to Andrew