In our new network we have multiple 3512 switches. One or two of them have the strange behavior to reset all ports every 1 hour exactely. All led's go off and on again immediately. The disconnection lasts less than 1 sec, because a continueus 1sec ping from one or more connected hosts do not show packet loss, but applications with an open connection to a server lose these connections and freak out. What causes this? There are no errors in the switch's logs and there are no other connection problems. We monitored the traffic over the network and did not see any strange or extraordinary things. We have some other Cisco hardware in our network, like a VPN router, but nothing special.