Hosts on the visitor network that are seen as 'scanning hosts', including those that might be running SKYPE (A possible (often probable) cause is running skype in the background. Closing skype does not actually shut it down. You must exit from the toolbar icon (or kill it from the task manager). Also after closing bit torrent, the application (btdna.exe), may still appear in the task manager and will need closing from there) as a supernode (or some other P2P software, we have also seen instances of an AFS client looking at all the cells in an AFS tree, e.g. using ls /afs/* or find /afs) will be put in the 'penalty box'. A scanning host being a host seen opening many tcp sessions in a very short time.
The penalty box reduces that machines network connection outside the visitor network to a shared 56kbps connection with other machines that are in the penalty box, thus drastically reducing their network speed and throughput.
Once in the penalty box the machine remains there for some amount of time. If it is seen again as a scanning host it is put in again. The only way to get out of the penalty box is to not be seen as a scanning host subsequently.
The host is released from the penalty box at the next 15 minute interval after the traffic ends, but it may take somewhat longer for the traffic to actually stop. The other end of the connection(s) may continue to attempt to use your host as the intermediary for file transfers for a time (which depends on the other P2P clients). P2P apps (of all types/clients) are intentionally greedy and sticky regarding potential intermediaries for transferring content.
The current list of hosts in the penalty box is provided.