It's a guess, but most likely it's a wrong un. Getting the file read mode wrong is unlikely to cause a crash that would trigger Window's error reporting.

Although the OP didn't give us enough code to reproduce the problem, he did give us enough information to provide some pointers and there was nothing there that indicated file I/O related problems.

I don't believe this is an I/O related problem. here's the relevant code

use Math::Random::MT::Auto::Range;
   my $rng = Math::Random::MT::Auto::Range->new(LO => 10000, HI => 999
+99,TYPE => 'INTEGER');
    my $A = $rng->rrand();
    my $B = $rng->rrand();
    my $str = "$A$B";
[download]

of course, when I comment it out, my file compiles, so I know this is the cause of the problem.

Your code runs fine for me. I've edited it a little to report versions:

use strict;
use warnings;
use Math::Random::MT::Auto::Range;

my $rng = Math::Random::MT::Auto::Range->new (
    LO   => 10000,
    HI   => 99999,
    TYPE => 'INTEGER'
);
my $A = $rng->rrand ();
my $B = $rng->rrand ();
my $str = "$A $B";

print "perl version $]\n";
print "Math::Random::MT::Auto::Range version $Math::Random::MT::Auto::
+Range::VERSION\n";
print $str;
[download]

which for me prints:

perl version 5.010001
Math::Random::MT::Auto::Range version 6.16
33649 69127
[download]

with the numbers in the last last line varying as expected from run to run. I'm running it on Windows XP btw.

True laziness is hard work

Oh, and you could simplisticly provide a replacement by:

use strict;
use warnings;
use Math::Random::MT qw();

package Range;

sub new {
    my ($class, %params) = @_;

    return bless \%params, $class;
}

sub rrand {
    my ($self) = @_;
    my $num = Math::Random::MT::rand ($self->{HI} - $self->{LO}) + $se
+lf->{LO};

    $num = int $num if $self->{TYPE} eq 'INTEGER';
    return $num;
}


package main;

my $rng = Range->new (
    LO   => 10000,
    HI   => 99999,
    TYPE => 'INTEGER'
);
my $A = $rng->rrand ();
my $B = $rng->rrand ();
my $str = "$A $B";

print "perl version $]\n";
print "Math::Random::MT version: $Math::Random::MT::VERSION\n";
print $str;
[download]

True laziness is hard work