I run a small computer lab made up of 10 computers of identical hardware and software (Dell Latitudes with Windows 7 x64 Enterprise) and I use a ZyWALL 2WG as a router/firewall. Nine of the computers connect to the router over wifi using WPA2-PSK encryption while the last one is connected by ethernet cable.

I'm having a problem where any computer connected to the wi-fi occasionally drops off the network (it cannot be pinged and the client cannot ping the gateway). It only happens on the wifi side and only when the encryption is WPA2-PSK or WPA-PSK. I tried using another router with a different make and model and had no problems. Thinking it could be a software error, I reset the router to factory defaults and installed the newest firmware (V4.04(AQI.8) | 04/09/2010), but still have the problem. The 802.1X log gives the following error User logout because of user disassociation. with this note WPA2-PSK:00242c582ece:logout where 00242c582ece is the mac address of the device.

At this point I'm out of things to try and leads to follow. It looks like this user had the same or similar problem, but none of those proposed solutions work for me.