AIS 7.0.1426 : Problem with realtime firewall traffic chart

Hello,
I have AIS 7.0.1426 (3 pc) and I have a trouble to see an activity on firewall trafic chart on 1 pc , I have statistics for others shields (files,mails,web,…) but nothing for activated firewall , even with clean reset.
pc1 : winxppro Sp3 => this one there is firewall chart pb
pc2 : winxppro Sp3 => OK for all charts shields and firewall
pc3 : win7 home => OK for all charts shields and firewall

Ps:I can see some activity in network connection tab (port , programs activity) but nothing on IN/OUT bytes

Thanks if you have something for me (and sorry for my english)

Edit:all 3 pc with firefox 10.0.2

Edit2:it’s not became just now with an update , It was already like this with V6 version , if I look in annual stats , there was some trafic before september 2011 , but I don’t remember what changes happened at this time in my computer :frowning: