I like to clean up the PATH as well when faced with such an operation (where I am preparing to run external programs and may be adding or removing pathels [path-list elements]).

Here's a little code to prepare the PATH so that it is less likely to cause problems.

#!perl

use Memoize;
use Win32;
use strict;

sub sp {
    my $pn;
    die unless @_ and (($pn)=shift);
    warn "No such directory: \"$pn\"" && return undef unless -d $pn;
    ($pn = Win32::GetShortPathName($pn)) =~ s{\\}{/}g;
    substr ($pn, 1+rindex($pn,'/')) = lc substr ($pn, 1+rindex($pn,'/'
+));
    $pn
}
sub smorp {
    my ($piece) = @_;
    $piece =
        lc $piece eq 'system32'
     ?      'system32'
     :  uc $piece eq 'WINDOWS'
     ?      'WINDOWS'
     :  $piece;
     return "/".$piece;
}


memoize('sp');
memoize('smorp');

BEGIN { use Env qw/@PATH/; use vars ('@thePATH', '%Uniqueness'); }
@thePATH = @PATH;
@PATH = ();

PONGO:
for my $ele (@thePATH)
{
    my $npiece;
    my @shattered = grep {$_} split /(?:[\\\/]+|:)+/ , $ele;
    my $backtog = index ($ele, ":") == 1 ?  # is it <D>:   ?
           uc(shift @shattered).":"
         :        $ele =~ m#[\\/]{2}#    ?  # or is it UNC ?
           "//".shift (@shattered)
         : do { die "UNRECOGNIZED PATHEL FORMAT" };
  BLA:
    {
      $backtog .= smorp ($npiece)  while @shattered
              && index (($npiece = shift @shattered)," ") == -1;
      unless (@shattered)
             {
               $Uniqueness{lc $backtog}++ and
                  print "# DUPLICATE element skipped (\"$backtog\")\n"
               or print "$backtog\n"; # or add to an array, or whateve
+r you need to do.
               next PONGO
             }
    # print "SPACES IN ${backtog}/${npiece}\n";
      $backtog = sp("${backtog}/${npiece}");
      redo BLA;
    }
    die "Reached code branch we should never see!";
}
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