Event[0]:
  Log Name: Microsoft-Windows-GroupPolicy/Operational
  Source: Microsoft-Windows-GroupPolicy
  Date: 2014-06-26T13:58:04.290
  Event ID: 7320
  Task: N/A
  Level: Error
  Opcode: Info
  Keyword: N/A
  User: S-1-5-18
  User Name: NT AUTHORITY\SYSTEM
  Computer: hostname
  Description: 
Error: Computer determined to be not in a site. Error code 0x77F.

Event[1]:
  Log Name: Microsoft-Windows-GroupPolicy/Operational
  Source: Microsoft-Windows-GroupPolicy
  Date: 2014-06-26T12:32:30.009
  Event ID: 7320
  Task: N/A
  Level: Error
  Opcode: Info
  Keyword: N/A
  User: S-1-5-21-1024758968-3939101906-3775097912-6653
  User Name: whatever
  Computer: hostname
  Description: 
Error: Computer determined to be not in a site. Error code 0x77F.

##</code><code>##


use strict;
use warnings;


# global vars
my ( $hash_ref, $logname, $source, $date, $evt_id, $error, $description) ;

# we'll increase this after every line in the while loop
my $count = 1;

# get every line and save it in $line.
# then separate the lines in $key/$value pairs divided by ':' 
while ( my $line = <DATA> ) {

    # a paragragh is a line
    $/ = "";

    chomp $line;
    my @line = split( /[\n\r]/, $line );

    for (@line) {
        next if $_ =~ /^\w+.*$/;
        next if $_ =~ /\s+Description.*$/;
        my ( $key, $value ) = split(/: /);
        if ( $key =~ m/^\s+Log Name.*$/ ) {
            $logname = $value;
        }
        elsif ( $key =~ m/^\s+Source.*$/ ) {
            $source = $value;
        }
        elsif ( $key =~ m/^\s+Date.*$/ ) {
            $date = $value;
        }
        elsif ( $key =~ m/^\s+Event ID.*$/ ) {
            $evt_id = $value;
        }
        elsif ( $key =~ m/^\s+Level.*$/ ) {
            $error = $value;
        }

        $hash_ref->{$count} = {
            Logname    => $logname,
            Source     => $source,
            Date       => $date,
            "Event ID" => $evt_id,
            Error      => $error,
        };

    }
    $count++;
}

use Data::Dumper;
print Dumper $hash_ref;

__DATA__
here is the dump with the format at the beginning


##</code><code>##


        $hash_ref->{$logname} = {
            Logname    => $logname,
            Source     => $source,
            Date       => $date,
            "Event ID" => $evt_id,
            Error      => $error,
        };