The same two servers as in thread http://social.technet.microsoft.com/Forums/en-US/winserversecurity/thread/a3603732-6d4d-4107-a2c9-fdcb64980dfe, with a new problem. One server is DC of a top level domain (dom.local). The other is DC of a child domain in the same forest (sub.dom.local). I am logged on to the sub.dom.local DC, with an enterprise admin account of dom.local. The start menu is configured to show the control panel as a submenu, and that works. Now the connection fails - I simulate this by unplugging the network cable from the dom.local DC (i.e. the other server, not the one I am at). Result: when I open the start menu and hover my mouse over the Control Panel item, nothing happens for a while (I assume a time-out contacting dom.local), after which the menu appears as a single greyed-out item labeled "(Empty)". I expected that re-plugging the network cable in the dom.local DC would fix this, but after waiting for a few minutes, there's still no change: my control panel on the sub.dom.local DC remains "(Empty)". Log off and back on to the sub.dom.local DC: logging on takes longer than normal, as if the dom.local DC is still inaccessible. After logging on, the control panel *still* remains "(Empty)". It remains that way until one of the servers has been rebooted. It doesn't matter which one I reboot, either one will do. This is repeatable, they did it every time I tried, and kept doing it until I rebooted either server.