What permissions do users or groups have?       
     On security tab of properties of the object, in Advanced --> Effective Permissions, we should select the Select button then write name of the user or group to check what permissions are applied on the user or group. Then we can check what combination of permissions applied improperly.
Note: the best applying permission is selecting a wide open permission in share permission for everyone group but select the main permissions in NTFS permission on the objects