Wireless connection drops spontaneously when idle

[Matthew Saltzman <mjs clemson edu>]

Fully up2date Fedora 8, kernel-2.6.25.4-10.fc8.x86_64,
NetworkManager-0.7.0-0.6.7.svn3370.fc8.x86_64,
wpa_supplicant-0.5.10-4.fc8.x86_64, dbus-1.1.2-9.fc8.x86_64, wireless
driver iwl3945.

Connection is WPA2 or WEP (both types fail).  Address assigned by DHCP.
If I keep pinging a machine on the net, the connection stays up, but if
I let the connection go idle, it drops, apparently around lease renewal
time.  This network keeps renewal times short (a matter of minutes), so
the connection drops every few minutes.

Excerpts from /var/log/messages with a renewal while pinging and one
while idle seem to show that NM fails to take some action:

        Jun  9 09:59:28 valkyrie dhclient: DHCPREQUEST on wlan0 to
        1.1.1.1 port 67
        Jun  9 09:59:28 valkyrie dhclient: DHCPACK from 1.1.1.1
        Jun  9 09:59:28 valkyrie NetworkManager: <info>  DHCP: device
        wlan0 state changed bound -> renew
        Jun  9 09:59:28 valkyrie dhclient: bound to 172.22.0.6 --
        renewal in 436 seconds.
        
        Jun  9 10:00:23 valkyrie dhclient: DHCPREQUEST on wlan0 to
        1.1.1.1 port 67
        Jun  9 10:00:23 valkyrie dhclient: DHCPACK from 1.1.1.1
        Jun  9 10:00:23 valkyrie dhclient: bound to 172.22.5.194 --
        renewal in 452 seconds.

It worked last week.  Any clue what's failing?

Will try backing up to previous kernel next.

Thanks.
-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs