Wireless systems
Lost signals with wireless connections can cause connection loss.
The latest technology to use is 802.11(a,b or g). This is great at avoiding the wire mess, but there is a new risk. Under Windows™, if you are using a plugged in or built-in wireless card, the interface goes offline if the signal is lost for even a second. When this happens, it is treated similar to unplugging your network cable. The Windows drivers report to the network stack that the interface is now offline, and everything associated with that interface is removed. If an application has an open channel, it is signaled that it has closed. As a result, you lose all your connections and must wait for your signal to return in order to log in again.
A possible workaround is to use an external wireless device that doesn't take the connection down when the signal is lost. This works because it doesn't look like the cable was unplugged when it loses signal, so Windows doesn't know there is a problem. When the signal returns, everything works just at before.