I have been playing a lot of Wolfenstein. Enemy Territory lately. Good game.
If you have more than one machine on your network at home though connecting to the same server, PunkBuster will kick you for all kinds of reasons.
I have seen errors such as "no packet flow", "server disconnected", "kicked for x minutes" etc.
The reason is because the net_ip and net_port variables are the same. net_ip is always set to localhost by default. you need to change this on one or more of the machines that are running ET.
The undocumented way round this is as follows:
When in the menu, open the console,
type the following
replace {0} with the name of your machine
\set net_ip "{0}"
replace {1} with a port number of your choice.
\set net_port {1}
Now punkbuster will not kick you.
You can also create a batch file, and use the commandline