Impossible de mettre norton à jour

salut,

je n'arrive pas à mettre mon antivirus norton à jour,

j'ai ce message qui s'affiche :

"Liveupate could not find all of the files it needed to run. Liveupdate was either not installed correctly or some of its files was inadvertantly deleted. You need to reinstall liveupdate before you can update your Symantec products".

C'est quoi le liveupdate ?

que dois je faire ?

merci d'avance.