Random Number Generator Problem

[blchrist@terpalum.umd.edu (Brien)]

Preface: I'm using GNAT on a windows box.

I'm generating a series of unsigned 64 bit integers and I get the same
value for about half of the results.  The ada built-in random number
generator seems to be giving me 2**63 much more often than any other
number.  I can't figure out why this would be.  Here is some sample
code to demonstrate my problem.

with Interfaces;
with Ada.Numerics.Discrete_Random;
with Ada.Text_Io;
use Ada.Text_Io;
procedure Generate_Random_Test is 
   type Unsigned_Dbl_Integer is new Interfaces.Unsigned_64; 
   package Rand is new
Ada.Numerics.Discrete_Random(Unsigned_Dbl_Integer);
   Rand_Gen : Rand.Generator;  
begin
   for I in 1..1000 loop
      Put_Line(Unsigned_Dbl_Integer'Image(Rand.Random(Rand_Gen)));
   end loop;

end Generate_Random_Test;


When I run this code, i get 9,233,........,808 (which is 2**63) as
about half of my results.

Thanks for the help!