ADuC702x power on error

I met a problem when I power on my custom board. The ADuC7021 on it can't reset correctly sometimes:

  • Programmer doesn't run;
  • All I/O pins are at high level.

Here is aduc part of schematic.

Net +3.3V in the schematic connects to a PC power module. And I found that if I turn on the switch of the module, this problem occurs occasionally. But if I plug borad's the power lines to the module while the module is already working, this problem NEVER comes.

 

I don't know how to deal with it, anybody have ideas