What, you don't know what operating you are running?

At any rate, you may or may not have read that tutorial I listed by now but for anybody else lurking around as Anonymous you might consider doing this to see for yourself what might be wrong:

use strict;  
use warnings; 
use File::Copy;
use File::Find;
use Cwd qw|cwd|;
my $modem_build_ms = 'I have no clue what should go into model_build_m
+s';
my $modem_build_location;

my $dir=$ARGV[0];
my $currdir = Cwd::cwd();

print $dir;

opendir(DIR, "$dir") || die "Error in opening dir $dir $!";
#die "Bad directory" unless (-d $dir);

print "\n$modem_build_ms\n";
my %files = map {$_ => 1} qw(data.txt datascript.pl);

find(sub {
    copy($File::Find::name, $currdir) or die "Can't cp $File::Find::na
+me : $! " 
       . Cwd::cwd() if delete $files{$_};
        
}, $dir);
close DIR;
__END__

Notice how the output says this: 

I have no clue what should go into model_build_ms
Can't cp ./other/data.txt : No such file or directory C:/Temp/abba/oth
+er at (eva
l 24) line 20.
[download]

I ran this code like this C:\Temp\abba>perl  runall.pl ./other which means that somewhere somebody moved me down into the target folder. If you run this with the argument to the script as the FULL file path however c:/temp/abba/other the code runs as expected.