Lpc2000

I've got the following code to start the ADC.  If I put in a 
breakpoint somewhere after the code and run to the breakpoint it will 
enter an endless loop.  If I step manually past the while statement 
and than run to the breakpoint it will work fine.  If I put in a delay 
before the while statement it also works but this seriously slows down 
the ADC.  I guess this has something to do with initialization but I'm 
not sure.  Does anyone have any ideas?
Thanks,
Dewayne

	ADCR = (ADCR & 0xFFFFFF00) | (1 << 1) | (1 << 24);

        //wait til done
     
	while((ADDR & 0x80000000) == 0)
	  ;

	//get result
	return (ADDR>>6) & 0x3FF;