ath seeming to lose carrier arbitrarily

thinkpad t40p
current as of today

connectivity is fine

    # ping psg.com
    PING psg.com (147.28.0.62): 56 data bytes
    64 bytes from 147.28.0.62: icmp_seq=0 ttl=44 time=176.850 ms
    64 bytes from 147.28.0.62: icmp_seq=1 ttl=44 time=172.591 ms
    ^C
    --- psg.com ping statistics ---
    2 packets transmitted, 2 packets received, 0% packet loss
    round-trip min/avg/max/stddev = 172.591/174.721/176.850/2.129 ms

some time later, suddenly, connectivity seems to have gone away

    # ping psg.com
    PING psg.com (147.28.0.62): 56 data bytes
    ping: sendto: No buffer space available
    ping: sendto: No buffer space available
    ^C
    --- psg.com ping statistics ---
    2 packets transmitted, 0 packets received, 100% packet loss

hmmm.  it dropped carrier.

well, just ifconfig it manually

    # ifconfig ath0 mode 11b ssid ripemtg channel 6

no immediate result

    # ifconfig ath0
    ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	    inet 193.0.9.131 netmask 0xfffffe00 broadcast 193.0.9.255
	    ether 00:05:4e:41:ee:cd
	    media: IEEE 802.11 Wireless Ethernet autoselect mode 11b (DS/1Mbps)
	    status: no carrier
	    ssid ripemtg 1:ripemtg
	    channel 6 authmode OPEN powersavemode OFF powersavesleep 100
	    wepmode OFF weptxkey 1

but ten seconds later, it is magically ok

    # ifconfig ath0
    ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	    inet 193.0.9.131 netmask 0xfffffe00 broadcast 193.0.9.255
	    ether 00:05:4e:41:ee:cd
	    media: IEEE 802.11 Wireless Ethernet autoselect mode 11b (DS/11Mbps)
	    status: associated
	    ssid ripemtg 1:ripemtg
	    channel 6 authmode OPEN powersavemode OFF powersavesleep 100
	    wepmode OFF weptxkey 1

no one sitting near me at the ripe meeting sees a carrier drop

randy