GPO Backup Failed ( Windows 2008 R2 )

Hello,

I'm trying to Backup one of the GPO but unable and found following Error LOGs.

Any Ideas Please.

=============================================================================================

GPO: SSS...Failed

The overall error was: Invalid pointer
Additional details follow.

[Warning] The security principal [S-1-5-21-2052111302-630328440-839522115-12724] referenced in extension [Security] cannot be resolved, but the task will continue. In the future, you can use a migration table to map or remove this security principal.
Details: No mapping between account names and security IDs was done.
 
[Warning] The security principal [S-1-5-21-2052111302-630328440-839522115-13057] referenced in extension [Security] cannot be resolved, but the task will continue. In the future, you can use a migration table to map or remove this security principal.
Details: No mapping between account names and security IDs was done.
 
[Warning] The security principal [S-1-5-21-2052111302-630328440-839522115-14042] referenced in extension [Security] cannot be resolved, but the task will continue. In the future, you can use a migration table to map or remove this security principal.
Details: No mapping between account names and security IDs was done.
 
[Warning] The security principal [S-1-5-21-2052111302-630328440-839522115-1604] referenced in extension [Security] cannot be resolved, but the task will continue. In the future, you can use a migration table to map or remove this security principal.
Details: No mapping between account names and security IDs was done.
 
[Warning] The security principal [S-1-5-21-2052111302-630328440-839522115-19552] referenced in extension [Security] cannot be resolved, but the task will continue. In the future, you can use a migration table to map or remove this security principal.
Details: No mapping between account names and security IDs was done.
 
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Log Name:      Application
Source:        Group Policy Management
Date:          5/12/2013 8:39:36 AM
Event ID:      2004
Task Category: None
Level:         Error
Keywords:      Classic
User:          SSS\admin
Computer:      SSS-DC2-AD1.SSS.com.
Description:
Backup of GPO failed. Error [Invalid pointer
].
 Details -
     Source GPO:
          DisplayName: SSS
          ID: {091E97B0-9196-4EA2-A1C8-2598EA180DB1}
          Domain: SSS.com.
 
      Backup:
         Directory: C:\Users\admin\Desktop
         Instance : {48F600BD-5287-4829-B055-7DE176DF620C}
         Comment  :
 
 
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Group Policy Management" />
    <EventID Qualifiers="49152">2004</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2013-05-12T05:39:36.000000000Z" />
    <EventRecordID>1004030</EventRecordID>
    <Channel>Application</Channel>
    <Computer>SSS-DC2-AD1.SSS.com.</Computer>
    <Security UserID="S-1-5-21-2052111302-630328440-839522115-27870" />
  </System>
  <EventData>
    <Data>Invalid pointer
</Data>
    <Data>SSS</Data>
    <Data>{091E97B0-9196-4EA2-A1C8-2598EA180DB1}</Data>
    <Data>SSS.com.</Data>
    <Data>C:\Users\admin\Desktop</Data>
    <Data>{48F600BD-5287-4829-B055-7DE176DF620C}</Data>
    <Data>
    </Data>
  </EventData>
</Event>
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Regards,Ali