Turn Off / Shut Down option of windows xp disappear

Few days ago, my pc was affected by trojon from msn. Button of Turn off Computer is disappeared. After google hard for the solution, I finally solved it. The solution is :

• Open Registry Editor by typing regedit in the Start, Run dialog.
  
• Navigate to the following locations:

HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer

-and-

HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer

• In the right-pane, double-click the value NoClose and set it to 0.
  
• Restart Windows for the changes to take effect

the original source : http://windowsxp.mvps.org/noclose.htm