About open_port and epipe error

[钱晓明]

Hi, I use open_port to run .exe file under windows xp:
     Port = open_port({spawn, "./algorithm/algorun"}, [{packet, 2}]),
     link(Port),
     Port ! {self(), {command, TaskContent}},
I run this executable file 5 times, and it do nothing but only show a
message box(do not read/write anything). I find that when they stop
normally( I click the message box, and return 0 in main function), only the
first one make my erlang module receiving {'EXIT', Port, normal}, the
others are {'EXIT', Port, epipe}.

So why I receive this epipe error? I am using Erlang R13B04 (erts-5.7.5).

Thanks!