If I've understood correctly, something along these lines might break your data into the records you need.

use strict;
use warnings;

my @records    = ();
my $inRecord   = 0;
my $rxRecStart = qr{^System:};
my $rxRecStop  = qr{^CPU\sTTY};
my $recordStr  = q{};

while( <DATA> )
{
    next if m{^\s*$};
    if( m{$rxRecStart} )
    {
        $inRecord = 1;
        push @records, $recordStr if $recordStr;
        $recordStr = $_;
    }
    elsif( m{$rxRecStop} )
    {
        $inRecord = 0;
        push @records, $recordStr if $recordStr;
        $recordStr = q{};
    }
    else
    {
        $recordStr .= $_ if $inRecord;
    }
}

foreach my $record ( @records )
{
    print $record, q{+} x 50, qq{\n};
}

__END__
System: hpnclass Thu Feb 12 16:31:02 2009
Load averages: 0.51, 0.45, 0.49
541 processes: 483 sleeping, 58 running
Cpu states: (avg)
 LOAD   USER   NICE    SYS   IDLE  BLOCK  SWAIT   INTR   SSYS
 0.51  14.7%   3.0%  18.3%  63.9%   0.0%   0.0%   0.0%   0.0% 

Memory: 13706264K (11030248K) real, 18023572K (14848696K) virtual, 216
+916K free  Page# 1/109

CPU TTY  PID USERNAME PRI NI   SIZE    RES STATE    TIME %WCPU  %CPU C
+OMMAND
 1   ?    50 root     152 20 16032K 16032K run   17565:36 24.94 24.89 
+vxfsd
 2   ? 17979 ora102st 154 24  3989M  3588K sleep  384:22  4.65  4.65 o
+ra_s002_pay9
 0   ?  2553 ora102st 154 24  3991M  5520K sleep 3308:08  3.47  3.47 o
+ra_s000_pay9
 3   ?  6585 root     154 24   250M 63652K sleep 10144:59  3.27  3.27 
+ucsrvwp
 1   ? 17085 ora102st 154 24  3989M  5340K sleep  218:26  2.73  2.72 o
+ra_s001_pay9
System: hpnclass Thu Feb 12 16:36:07 2009
Load averages: 0.52, 0.50, 0.50
520 processes: 461 sleeping, 59 running
Cpu states: (avg)
 LOAD   USER   NICE    SYS   IDLE  BLOCK  SWAIT   INTR   SSYS
 0.51  14.7%   3.0%  18.3%  63.9%   0.0%   0.0%   0.0%   0.0% 

Memory: 13706264K (11030248K) real, 18023572K (14848696K) virtual, 216
+916K free  Page# 1/109

CPU TTY  PID USERNAME PRI NI   SIZE    RES STATE    TIME %WCPU  %CPU C
+OMMAND
 1   ?    50 root     152 20 16032K 16032K run   17565:36 24.94 24.89 
+vxfsd
 2   ? 17979 ora102st 154 24  3989M  3588K sleep  384:22  4.65  4.65 o
+ra_s002_pay9
 0   ?  2553 ora102st 154 24  3991M  5520K sleep 3308:08  3.47  3.47 o
+ra_s000_pay9
 3   ?  6585 root     154 24   250M 63652K sleep 10144:59  3.27  3.27 
+ucsrvwp
 1   ? 17085 ora102st 154 24  3989M  5340K sleep  218:26  2.73  2.72 o
+ra_s001_pay9
[download]

The output.

System: hpnclass Thu Feb 12 16:31:02 2009
Load averages: 0.51, 0.45, 0.49
541 processes: 483 sleeping, 58 running
Cpu states: (avg)
 LOAD   USER   NICE    SYS   IDLE  BLOCK  SWAIT   INTR   SSYS
 0.51  14.7%   3.0%  18.3%  63.9%   0.0%   0.0%   0.0%   0.0%
Memory: 13706264K (11030248K) real, 18023572K (14848696K) virtual, 216
+916K free  Page# 1/109
++++++++++++++++++++++++++++++++++++++++++++++++++
System: hpnclass Thu Feb 12 16:36:07 2009
Load averages: 0.52, 0.50, 0.50
520 processes: 461 sleeping, 59 running
Cpu states: (avg)
 LOAD   USER   NICE    SYS   IDLE  BLOCK  SWAIT   INTR   SSYS
 0.51  14.7%   3.0%  18.3%  63.9%   0.0%   0.0%   0.0%   0.0%
Memory: 13706264K (11030248K) real, 18023572K (14848696K) virtual, 216
+916K free  Page# 1/109
++++++++++++++++++++++++++++++++++++++++++++++++++
[download]

I hope this is of use.

Cheers,

JohnGG

Update: Corrected logic error in first if clause which was stripping the first line of the data wanted.