Hello Fadua,
Please visit http://www.microsoft.com/genuine. Please locate the "Validate Windows" button in the upper right hand corner and click it. Just follow the directions and you should vaidate windows. Should you have any complications please download and run the utility at this link http://go.microsoft.com/fwlink/?linkid=52012 , then click the Windows tab, Copy to Clipboard, then paste the report into a New Post on this Forum.
Step 2 is tell us about the COA. Tell us:
1. What edition of Windows XP is it for, Home, Pro, or Media Center?
2. Does it read "OEM Software" or "OEM Product" in black lettering?
3. Or, does it have the computer manufacturer's name in black lettering?
4. DO NOT post the Product Key.
5. Please also provide a short description of the issue you are experiencing.
NOTE: The data collected with the Genuine Diagnostics Tool does NOT contain any information that can personally identify you and can be fully reviewed, by you, before being posted.
Thank you,
Stephen Holm, MS