自己レス

今日、久しぶりにLAN-W300N/U2をつないでみたら今まではＷＥＰのみ接続可能でしたが、
WPA/WPA2にて接続ができるようにになっていました。
先日のアップデートの影響かあ

LAN-W300N/U2はrt2870staとrt2800usbの2つのドライバにIDがあるので動作に問題を起こしているのでしょう。

対策：
1.#1の操作を元に戻してからrt2870staをblacklistに指定してrt2800usbを使う。
2.rt2800usbをblacklistに指定してrt2870staを使う。

11.04ではdatファイル関連のエラーがでないのでrt2870staがdatファイルを必要としているのかどうか分かりませんが、以前のフィルの場所は、/etc/Wireless/RT2870STA or RT3070STA/RT2870STA.dat or RT3070STA.datになります。

Ｙａｓｕｓｈｉ０４と言いますが、takasi_sの回答を見て気になり　自分のパソコンでしらべました。
さて、同じ無線ＬＡＮ子機を利用していますが、実害ないのでそのままにしていました
ADSL回線上の理由　１２Ｍの契約のため
ＯＳは、ubuntu11.04

無線ＬＡＮ　
yasushi2010@yasushi2010-PCV-J15:~$ iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

wlan0     Ralink STA  ESSID:"*****"  Nickname:"RT2870STA"
          Mode:Managed  Frequency=2.472 GHz  Access Point: **:**:8E:**:**:** 
          Bit Rate=54 Mb/s   
          RTS thr:off   Fragment thr:off
          Link Quality=100/100  Signal level:-59 dBm  Noise level:-83 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

dmesgの結果（無線ＬＡＮに関係すると思われる墓所　こちらでは、エラーがないように見える

[   15.434365] Adding 5994492k swap on /dev/sda9.  Priority:-1 extents:1 across:5994492k
[   15.669462] <30>udev[279]: starting version 167
[   15.774634] EXT4-fs (sda8): re-mounted. Opts: errors=remount-ro,user_xattr
[   16.108136] lp: driver loaded but no devices found
[   16.245999] rt2870sta: module is from the staging directory, the quality is unknown, you have been warned.
[   16.487261] rtusb init --->
[   16.490440] === pAd = d7b71000, size = 472668 ===
[   16.490456] <-- RTMPAllocAdapterBlock, Status=0
[   16.537199] usbcore: registered new interface driver rt2870
[   17.357628] type=1400 audit(1307613410.767:2): apparmor="STATUS" operation="profile_load" name="/sbin/dhclient" pid=416 comm="apparmor_parser"
[   17.369678] type=1400 audit(1307613410.779:3): apparmor="STATUS" operation="profile_load" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=416 comm="apparmor_parser"
[   17.370561] type=1400 audit(1307613410.779:4): apparmor="STATUS" operation="profile_load" name="/usr/lib/connman/scripts/dhclient-script" pid=416 comm="apparmor_parser"
[   18.461445] agpgart-sis 0000:00:00.0: SiS chipset [1039/0730]
[   18.655892] eth0: link down
[   18.660592] ADDRCONF(NETDEV_UP): eth0: link is not ready
[   18.725397] agpgart-sis 0000:00:00.0: AGP aperture is 64M @ 0xec000000
[   19.331946] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
[   19.443678] parport_pc 00:0a: reported by Plug and Play ACPI
[   19.443755] parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE]
[   19.542430] lp0: using parport0 (interrupt-driven).
[   20.150219] psmouse serio1: ID: 10 00 64
[   20.806083] input: ImPS/2 Logitech Wheel Mouse as /devices/platform/i8042/serio1/input/input3
[   22.960566] ppdev: user-space parallel port driver
[   23.106315] <-- RTMPAllocTxRxRingMemory, Status=0
[   23.118752] -->RTUSBVenderReset
[   23.118844] <--RTUSBVenderReset
[   23.432301] 1. Phy Mode = 0
[   23.432316] 2. Phy Mode = 0
[   23.432325] NVM is Efuse and its size =2d[2d0-2fc]
[   23.501167] RTMPSetPhyMode: channel is out of range, use first channel=1
[   23.517156] 3. Phy Mode = 0
[   23.537410] MCS Set = 00 00 00 00 00
[   24.173934] RTMPFilterCalibration - can't find a valid value, loopcnt=102 stop calibrating<==== rt28xx_init, Status=0
[   24.195516] 0x1300 = 00073200
[   24.613811] ---> RTMPFreeTxRxRingMemory
[   24.613940] <--- RTMPFreeTxRxRingMemory
[   24.706388] C-Media PCI 0000:00:0d.0: PCI INT A -> Link[LNKA] -> GSI 11 (level, low) -> IRQ 11
[   25.098727] <-- RTMPAllocTxRxRingMemory, Status=0
[   25.130696] -->RTUSBVenderReset
[   25.130812] <--RTUSBVenderReset
[   25.467622] 1. Phy Mode = 0
[   25.467638] 2. Phy Mode = 0
[   25.467647] NVM is Efuse and its size =2d[2d0-2fc]
[   25.555244] 3. Phy Mode = 0
[   25.572631] MCS Set = 00 00 00 00 00
[   25.647527] <==== rt28xx_init, Status=0
[   25.649763] 0x1300 = 00073200
[   25.839049] type=1400 audit(1307613419.247:5): apparmor="STATUS" operation="profile_load" name="/usr/share/gdm/guest-session/Xsession" pid=752 comm="apparmor_parser"
[   25.884698] type=1400 audit(1307613419.295:6): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=757 comm="apparmor_parser"
[   25.886279] type=1400 audit(1307613419.295:7): apparmor="STATUS" operation="profile_replace" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=757 comm="apparmor_parser"
[   25.887186] type=1400 audit(1307613419.295:8): apparmor="STATUS" operation="profile_replace" name="/usr/lib/connman/scripts/dhclient-script" pid=757 comm="apparmor_parser"
[   26.089340] vesafb: framebuffer at 0xf0000000, mapped to 0xd7d00000, using 3072k, total 3072k
[   26.089358] vesafb: mode is 1024x768x32, linelength=4096, pages=0
[   26.089365] vesafb: scrolling: redraw
[   26.089376] vesafb: Truecolor: size=8:8:8:8, shift=24:16:8:0
[   26.090463] Console: switching to colour frame buffer device 128x48
[   26.090618] fb0: VESA VGA frame buffer device
[   26.271231] type=1400 audit(1307613419.679:9): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince" pid=758 comm="apparmor_parser"
[   26.424855] type=1400 audit(1307613419.835:10): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince-previewer" pid=758 comm="apparmor_parser"
[   26.431576] type=1400 audit(1307613419.839:11): apparmor="STATUS" operation="profile_load" name="/usr/lib/cups/backend/cups-pdf" pid=778 comm="apparmor_parser"
[   26.455765] type=1400 audit(1307613419.863:12): apparmor="STATUS" operation="profile_load" name="/usr/sbin/cupsd" pid=778 comm="apparmor_parser"
[   26.539136] type=1400 audit(1307613419.947:13): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince-thumbnailer" pid=758 comm="apparmor_parser"
[   26.727504] type=1400 audit(1307613420.135:14): apparmor="STATUS" operation="profile_replace" name="/usr/lib/cups/backend/cups-pdf" pid=786 comm="apparmor_parser"
[   29.690826] sisfb: Video ROM found
[   29.696177] sisfb: Fatal error: Unable to reserve 16MB framebuffer memory
[   29.696194] sisfb: Is there another framebuffer driver active?
[   29.933425] [drm] Initialized drm 1.1.0 20060810
[   29.954106] pci 0000:01:00.0: PCI INT A -> Link[LNKA] -> GSI 11 (level, low) -> IRQ 11
[   29.954131] pci 0000:01:00.0: setting latency timer to 64
[   29.959029] [drm] Initialized sis 1.3.0 20070626 for 0000:01:00.0 on minor 0
[   29.963096] agpgart-sis 0000:00:00.0: AGP 2.0 bridge
[   29.963157] agpgart-sis 0000:00:00.0: putting AGP V2 device into 4x mode
[   29.963258] pci 0000:01:00.0: putting AGP V2 device into 4x mode
[   31.413712] EXT4-fs (sda8): re-mounted. Opts: errors=remount-ro,user_xattr,commit=0
[   32.016606] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[   35.856119] wlan0: no IPv6 routers present
[   37.375074] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[   37.377926] ==>rt_ioctl_siwfreq::SIOCSIWFREQ[cmd=0x8b04] (Channel=1)
[   39.230356] EXT4-fs (sda8): re-mounted. Opts: errors=remount-ro,user_xattr,commit=0
[   52.008613] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[   92.008660] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  101.840524] FAT: codepage cp437 not found
[  152.172664] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  232.012446] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  302.433339] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  302.441497] ==>rt_ioctl_siwfreq::SIOCSIWFREQ[cmd=0x8b04] (Channel=1)
[  332.008579] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  452.032440] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  572.008641] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  692.032463] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  812.008532] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[  932.008589] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1052.008546] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1172.008553] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1292.008575] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1412.008521] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1532.008755] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1652.008582] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1772.008802] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 1892.008455] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2012.008602] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2132.008636] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2252.008700] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2372.008525] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2492.008456] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2612.008546] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2732.008513] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2852.008606] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524
[ 2972.008572] ===>rt_ioctl_giwscan. 4(4) BSS returned, data->length = 524


rt2800usbを検索すると /usr/src/linux-headers-2.6.38-8-generic/include/config/rt2800usb のフォルダにrt33xx.h to
unknown.h　というファイルがありますが、中身は、なにもかかれていません。