Wireless Network Loses Connection

[JMJ_coder]

I have a wireless network setup up for my laptop - Lenovo T61 running NetBSD 5.0 RC1. I have wpa_supplicant configured and running:

# WPA_SUPPLICANT.CONF
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=wheel

# home network; AT&T DSL with 2701HG-B Gateway
network={
        ssid="######"
        scan_ssid=1
        key_mgmt=WPA-PSK
        psk="######"
}

It connects fine on bootup and such. The problem I have is that every 1-3 hours, the connection is 'lost' and I have to reinitialize the connection - restart wpa_supplicant, network, and dhclient.

I'm not certain why it loses the connection - whether it is a feature of WPA (though, I am actively using the link), or if it is just the nature of wireless, or something else?

Any ideas?