Most of the time the network manager doesn't connect to a network, although the signal is strong.
Sometimes it starts working after I dis/enable the wireless again.
This happens since 11.10 and it's really horrorble to use my Netbook (EeePC 1015PEM).
It worked some versions erlier. But I can't remember the version.
It also happens with other networks.

I reported this bug on launchpad first an was than asked to report it here as well. I don't know how to add the relevant files which were generated by apport to this site so I add the link to the relevant bug on launchpad.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/972670



ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: network-manager-gnome 0.9.3.995+git.20120313t141231.c89224f-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-20.33-generic-pae 3.2.12
Uname: Linux 3.2.0-20-generic-pae i686
ApportVersion: 1.95-0ubuntu1
Architecture: i386
Date: Tue Apr 3 19:31:35 2012
EcryptfsInUse: Yes
ExecutablePath: /usr/bin/nm-connection-editor
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120201.1)
IpRoute:

NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: network-manager-applet
UpgradeStatus: Upgraded to precise on 2012-03-02 (31 days ago)
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC269VB Analog [ALC269VB Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu2
Architecture: i386
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC269VB Analog [ALC269VB Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: sid 1906 F.... pulseaudio
CRDA:
 country DE:
  (2400 - 2483 @ 40), (N/A, 20)
  (5150 - 5250 @ 40), (N/A, 20), NO-OUTDOOR
  (5250 - 5350 @ 40), (N/A, 20), NO-OUTDOOR, DFS
  (5470 - 5725 @ 40), (N/A, 26), DFS
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf7cf8000 irq 45'
   Mixer name : 'Realtek ALC269VB'
   Components : 'HDA:10ec0269,1043841c,00100100'
   Controls : 16
   Simple ctrls : 9
DistroRelease: Ubuntu 12.04
EcryptfsInUse: Yes
HibernationDevice: RESUME=UUID=17f2c958-efa6-4175-a0d9-65311fb1410c
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120201.1)
MachineType: ASUSTeK Computer INC. 1015PEM
Package: linux (not installed)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-23-generic-pae root=UUID=82f8c228-d338-4bb0-b01d-33237d78d88d ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic-pae 3.2.14
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-23-generic-pae N/A
 linux-backports-modules-3.2.0-23-generic-pae N/A
 linux-firmware 1.78
SourcePackage: linux
Tags: precise precise
Uname: Linux 3.2.0-23-generic-pae i686
UpgradeStatus: Upgraded to precise on 2012-03-02 (43 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
dmi.bios.date: 08/13/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0606
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: 1015PE
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: x.xx
dmi.chassis.asset.tag: 0x00000000
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer INC.
dmi.chassis.version: x.x
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0606:bd08/13/2010:svnASUSTeKComputerINC.:pn1015PEM:pvrx.x:rvnASUSTeKComputerINC.:rn1015PE:rvrx.xx:cvnASUSTeKComputerINC.:ct10:cvrx.x:
dmi.product.name: 1015PEM
dmi.product.version: x.x
dmi.sys.vendor: ASUSTeK Computer INC.