local security policy setting (access this computer from the network)

ok! This problem is already exist to one of the forums.
I am unable to access to one of the computer of my network place. the message error is: (\\srv n'est pas disponible. vous ne disposez peut-?tre pas des autorisations n?ccessaires pour acc?der ? cette ressource r?seau. Contactez l'administrateur de ce serv eur pour savoir si vous disposez des autorisations d'acc?s.
?chec d'ouverture de session: l'utilisateur ne b?n?ficie pas du type d'ouverture de session demand? sur cet ordinateur.)

I went into the local security policy setting of this computer and saw that, "access this computer from the network" was blank. so i added all the groups that i saw from the other computer, and the problem was resolved. but few time ago i have the same problem, the setting was blank again; i added again the appropriate groups but it still be blank for fez time, i repeat the modification many times but the setting become blank everytime.

So now i asking for you help