Something wrong with Windows implementation?

More of a platform difference -- a thread used instead of a fork.

Use this instead:

use strict;
use warnings;

my $cmd = "tasklist";
my $pid = open PIPE, "-|", $cmd or die $!;

while (my $line = <PIPE> ) {
    print $line;
    last if $line =~ /^smss/;
}

close PIPE;
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