When I'm stumped I often try reducing the script to the bare bones to get something working and gradually add things back in.

Something like:

#!/usr/bin/perl

use warnings;
use strict;

my $dir = 'c:/Perl';

opendir DIR_A, $dir
  or die $!;
  
while(my $job = readdir(DIR_A)){
  print "$job\n";
}

__DATA__
---------- Capture Output ----------
> "C:\Perl\bin\perl.exe" _new.pl
.
..
bin
Desktop.ini
eg
html
lib
myperl
site
Tidy

> Terminated with exit code 0.
[download]

When you come up against the error you'll have a better chance of narrowing down the source of your grief.

Hope that helps.