ndis0 stops working after a while

[Leonardo M. Ramé]

Since a couple of weeks I noted my wireless connection (Broadcom 4310 ndis wrapper) stops working after a while, something like 10 minutes after I leave the notebook, a Dell Inspiron 1525. Then I have to ifconfig ndis0 down / ifconfig ndis0 up to reconnect. 

The notebook is connected via WiFi to a router (DLink Dir300), who has another PC with WinXP connected by cable, this PC doesn't looses the connection. 

I don't remember having upgraded anything network related. What can be causing this behavior?.

Below I copied a couple of config files I changed, specially dhclient.conf because I thought the problem was related to the DNS server of my ISP, but now I don't think that is the problem.

uname -a:
FreeBSD inspiron.local 7.2-RELEASE FreeBSD 7.2-RELEASE #0: Fri May  1 08:49:13 UTC 2009     root at walker.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

/boot/loader.conf
bcmwl5_sys_load="YES"
wlan_scan_ap_load="YES"
wlan_scan_sta_load="YES"
wlan_wep_load="YES"
wlan_tkip_load="YES"
snd_driver_load="YES"
hw.snd.default_unit=1
hint.hdac.0.config="gpio2"
hint.hdac.0.cad2.nid13.config="device=Speaker conn=Fixed"
vboxdrv_load="YES"
atapicam_load="YES"
sem_load="YES"

/etc/rc.conf
keymap="spanish.iso.acc"
inetd_enable="YES"
linux_enable="YES"
sshd_enable="YES"
moused_enable="YES"
rpcbind_enable="YES"
hald_enable="YES"
dbus_enable="YES"
amd_enable="YES"
fusefs_enable="YES"
ifconfig_ndis0="WPA DHCP"
hostname="inspiron.local"

/etc/dhclient.conf
# $FreeBSD: src/etc/dhclient.conf,v 1.3.34.1 2009/04/15 03:14:26 kensmith Exp $
#
#       This file is required by the ISC DHCP client.
#       See ``man 5 dhclient.conf'' for details.
#
#       In most cases an empty file is sufficient for most people as the
#       defaults are usually fine.
#
prepend domain-name-servers 4.2.2.1,4.2.2.2;

/etc/resolv.conf
nameserver 4.2.2.1
nameserver 4.2.2.2
nameserver 192.168.0.1

Thanks in advance,
Leonardo M. Ramé
http://leonardorame.blogspot.com