I've noticed that Folding blocks network connections whenever it tries to connect to submit work units. The problem has been bad lately because the work unit server is almost always down when the client needs to connect. This can last for more than 30 minutes, and almost all other connections are blocked during that outage. Any connections that are available are very slow, like being on a 2400 bps modem. The Mac isn't the problem because this also happens on another system running Linux. I looked at the netstat information and this is what appears to be the problem: Proto Recv-Q Send-Q Foreign Address (state) tcp4 0 33580 vspx85.stanford..8080 ESTABLISHED tcp4 0 33304 vspx85.stanford..8080 ESTABLISHED tcp4 0 23168 vsp50.stanford.e.8080 FIN_WAIT_1 The Folding console looks like this: Connecting to http://126.96.36.199:8080/ - Couldn't send HTTP request to server + Could not connect to Work Server (results) (188.8.131.52:8080) - Error: Could not transmit unit. Keeping unit in queue. When those Folding connections finally go through or the Folding client is shut down, the network behaves normally again.