SOLVED!

Special thanks to Grygonos, and thanks to everyone else who responded so quickly!! I adapted Grygonos' code, and managed to make it work, things that may have made a difference were the initial pwd chomp, and the use of \\\\ in places. for interest the working code follows, will probably adapt further but this works.

#!wperl 

use IO::File;
use strict;

my $dir = $ARGV[0];
chomp($dir);

$dir =~ s{\\}{\\\\}g;

mapMe($dir);

sub mapMe
{
    my $handle = shift;

    opendir(SPROUT,$handle);
    
    my @entries = readdir(SPROUT);

    closedir(SPROUT);
    
    foreach my $i (2..scalar(@entries))
    {
        my $param_handle = $handle."\\".$entries[$i];
        
        if(opendir(TEST,$param_handle) and $entries[$i])
        {
            closedir(TEST);    

            $handle =~ s{\\\\}{\\}g;
        
        my ($newdirname)= $handle."\\".$entries[$i]. "z";
        rename ($handle."\\".$entries[$i], $newdirname);
                    
            mapMe($newdirname);

        }
        elsif($entries[$i])
        {
        my ($newname) = $handle."\\".$entries[$i] . "z";
        rename ($handle."\\".$entries[$i], $newname);
        }
    }
}
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cheers!!
ant