Lpc2000

Dear sirs 
I met a very strange situation. I use LPC2105 in my simple test 
board, that has only a MAX3232 to connect to PC. I want to download 
program through this port. But when I use LPC210X to read the part 
ID, I got the failed message. When I use an Oscilloscope to watch the 
CLOCK and UART0 signal, the communication was successful, the ISP 
software got the part ID 4293984034 and the boot loader ID 1.3. Is 
this correct? I repeated several times. the result is -- 

1. power on the board then place the probe --- always fail 
2. place the probe then power on --- almost successful every time 
3. after successful connect, it will always be successful even if 
remove the probe. 

I guess it may be caused by the sequence of inner power and IO power. 
But no matter I power on the 1.8v or the 3.3V first and then the 
other, The board does not work. 

Who knows this reason and help me please. 

Richard