In a clean installation of Odoo (OCB) I created a new user's group for company's salespersons (Other Extra Rights / User: Own Customers Only) with this rule (salespersons only have access to their customers):

Object: Partner

Rule Definition: ['|',('user_id','=',user.id),('user_id','=',False)]

The problem is that users of this group cannot access res.user:

The requested operation cannot be completed due to security restrictions. Please contact your system administrator.

(Document type: res.users, Operation: read)

This happen, for example, trying to edit user's Preferences or trying to create a sale order.

Someone can help me to solve this problem?

Thanks.