Michel,
It's not a refresh issue on the toolbar.
The problem is in the treeview of the messages. For this login I don't see a Chatter section at all. I'm replying by getting your message from my inbox not from the top frame.
>Maybe the icon toolbar stopped refreshing. This is a known bug in IE where the META REFRESH tag stops working after a while. You just have to right click Refresh in that toolbar to restart it. We had that with the other design as well.