We are using a client/server versioning system (Perforce). Randomly, a client gets disconnected and is only able to reconnect when the user disables and re-enables the network card. The weird thing is that it happens with different users, hardware (including NIC chipsets) and moments of the day. The affected user can access to other servers on the same LAN and non-affected users are able to work with whatever they want, including Perforce, without any problem. What part of hardware/software I would most likely blame for that?