With -current kernel from around 20040119, userland somewhat more 
ancient
(about 200304??), after giving my system some work, like building a 
release,
its wireless interface has a nasty habit of going mute. Packets are 
still
being received, but nothing sent.

tcpdump shows inbound packets:
18:07:38.743723 192.168.254.130.50582 > 239.255.255.253.427: udp 49
18:07:39.760383 192.168.254.130.50583 > 239.255.255.253.427: udp 49
18:07:40.761346 192.168.254.130.50583 > 239.255.255.253.427: udp 49
18:07:41.761711 192.168.254.130.50583 > 239.255.255.253.427: udp 49
18:07:42.772844 192.168.254.130.50583 > 239.255.255.253.427: udp 49
18:08:03.890172 arp who-has 192.168.254.129 tell 192.168.254.130
18:08:04.890449 arp who-has 192.168.254.129 tell 192.168.254.130
18:08:05.891613 192.168.254.130.50584 > 239.255.255.253.427: udp 49
18:08:06.915670 192.168.254.130.50584 > 239.255.255.253.427: udp 49
18:08:07.916286 192.168.254.130.50585 > 239.255.255.253.427: udp 49

tcpdump with IEEE802_11 doesn't show much more:
18:14:18.052609 BSSID:0:5:5d:5b:c5:f5 SA:0:40:5:ae:bd:fc 
DA:ff:ff:ff:ff:ff:ff arp who-has 192.168.254.129 tell 192.168.254.130
18:14:18.052694 DA:ff:ff:ff:ff:ff:ff BSSID:0:5:5d:5b:c5:f5 
SA:0:40:5:ae:bd:fc arp who-has 192.168.254.129 tell 192.168.254.130
18:14:19.053208 BSSID:0:5:5d:5b:c5:f5 SA:0:40:5:ae:bd:fc 
DA:ff:ff:ff:ff:ff:ff arp who-has 192.168.254.129 tell 192.168.254.130
18:14:19.053304 DA:ff:ff:ff:ff:ff:ff BSSID:0:5:5d:5b:c5:f5 
SA:0:40:5:ae:bd:fc arp who-has 192.168.254.129 tell 192.168.254.130

When this happens, anything trying to send outbound, gets ENOBUFS:
ksh$ ping 192.168.254.130
PING 192.168.254.130 (192.168.254.130): 56 data bytes
ping: sendto: No buffer space available
ping: sendto: No buffer space available

Even AppleTalk:
Jan 25 18:12:30 stix-pc atalkd[687]: [main.c:628]: E:ATalkDaemon: 
as_timer sendto 0.255 (101): No buffer space available

"ifconfig down && ifconfig up" fixes it until next time. The only other
thing I've noticed is that the kernel prints a couple of "wi0: bad idx 
6e"
lines per hour. Anybody got any ideas where I should go from here?

Interface is:
wi0: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 
1500
         nwid xxxxxxxx
         powersave off
         bssid 00:05:5d:5b:c5:f5 chan 6
         address: 00:05:5d:5b:c5:f5
         media: IEEE802.11 autoselect hostap (DS2 hostap)
         status: active
         inet 192.168.254.129 netmask 0xffffff80 broadcast 
192.168.254.255
         inet6 fe80::205:5dff:fe5b:c5f5%wi0 prefixlen 64 scopeid 0x1
         atalk 101.1 range 101-101 phase 2 broadcast 101.1

wi0 at pci0 dev 8 function 0: Intersil Prism2.5 Wireless Lan
wi0: interrupting at irq 11
wi0: 802.11 address 00:05:5d:5b:c5:f5
wi0: using RF:PRISM2.5 MAC:ISL3874A(Mini-PCI)
wi0: Intersil Firmware: Primary (1.0.5), Station (1.3.4)
wi0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps

Cheers,
--
Paul Ripke
Unix/OpenVMS/TSM/DBA
I love deadlines. I like the whooshing sound they make as they fly by.
-- Douglas Adams