NM disconnects frequently on "wlan0: deauthenticating ... by local choice (reason=3)"

[ScayTrase]

Binary package hint: network-manager

my network-manager applet reconnects my WiFi very rapidly (about 2-3 times in 3-5 minutes).

my dmesg has repeating records like

[ 1203.280093] wlan0: deauthenticating from 00:25:62:fa:23:2b by local choice (reason=3)
[ 1203.321619] wlan0: deauthenticating from 00:25:62:fa:23:2b by local choice (reason=3)
[ 1203.321756] wlan0: direct probe to AP 00:25:62:fa:23:2b (try 1)
[ 1203.325362] wlan0: direct probe responded
[ 1203.325370] wlan0: authenticate with AP 00:25:62:fa:23:2b (try 1)
[ 1203.327151] wlan0: authenticated
[ 1203.327184] wlan0: associate with AP 00:25:62:fa:23:2b (try 1)
[ 1203.330274] wlan0: RX AssocResp from 00:25:62:fa:23:2b (capab=0x411 status=0 aid=1)
[ 1203.330281] wlan0: associated
[ 1203.390096] wlan0: deauthenticating from 00:25:62:fa:23:2b by local choice (reason=3)
[ 1203.391623] wlan0: deauthenticating from 00:25:62:fa:23:2b by local choice (reason=3)
[ 1203.392081] wlan0: direct probe to AP 00:25:62:fa:23:2b (try 1)
[ 1203.395360] wlan0: direct probe responded
[ 1203.395368] wlan0: authenticate with AP 00:25:62:fa:23:2b (try 1)
[ 1203.397238] wlan0: authenticated
[ 1203.397270] wlan0: associate with AP 00:25:62:fa:23:2b (try 1)
[ 1203.400333] wlan0: RX AssocResp from 00:25:62:fa:23:2b (capab=0x411 status=0 aid=1)
[ 1203.400340] wlan0: associated

scaytrase@scaytrase-laptop:~$ lsb_release -rd
Description: Ubuntu 10.04.1 LTS
Release: 10.04

network-manager:
  Установлен: 0.8-0ubuntu3
  Кандидат: 0.8-0ubuntu3
  Таблица версий:
 *** 0.8-0ubuntu3 0
        500 http://ru.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

my system is 64bit, but i`ve faced this fact much earlier, using 32bit.

network provided by access point and has WPA2 encryption.

ms windows working with the same network just fine, so i think problem is in my system.