i started working with ubuntu 11.10 last year. i upgraded to 12.04 a week back. since then i have had all sorts of problems with network connection.

first had to install the new driver. the hardware switch somehow got disabled then the above problem arrived. even tho the options are all enabled, the OS is not able to detect scan available network connections. also i have to bring to notice that once in a while it does get connected, can not explain how it happens. I want to fix this problem once and for all. please help.

ifconfig:

eth0      Link encap:Ethernet  HWaddr f0:4d:a2:51:b3:c8  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:44 

eth1      Link encap:Ethernet  HWaddr 1c:65:9d:67:d5:e1  
          inet6 addr: fe80::1e65:9dff:fe67:d5e1/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:170
          TX packets:0 errors:27 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:17 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:344 errors:0 dropped:0 overruns:0 frame:0
          TX packets:344 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:20336 (20.3 KB)  TX bytes:20336 (20.3 KB)

lshw -c network

 *-network               
       description: Wireless interface
       product: BCM4313 802.11b/g/n Wireless LAN Controller
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: eth1
       version: 01
       serial: 1c:65:9d:67:d5:e1
       width: 64 bits
       clock: 33MHz
       capabilities: bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=wl0 driverversion=5.100.82.38 latency=0 multicast=yes wireless=IEEE 802.11
       resources: irq:17 memory:f0500000-f0503fff
  *-network
       description: Ethernet interface
       product: AR8152 v1.1 Fast Ethernet
       vendor: Atheros Communications Inc.
       physical id: 0
       bus info: pci@0000:04:00.0
       logical name: eth0
       version: c1
       serial: f0:4d:a2:51:b3:c8
       capacity: 100Mbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI firmware=N/A latency=0 multicast=yes port=twisted pair
       resources: irq:44 memory:f0400000-f043ffff ioport:2000(size=128)

iwconfig

lo        no wireless extensions.

eth1      IEEE 802.11  Access Point: Not-Associated   
          Link Quality:5  Signal level:0  Noise level:196
          Rx invalid nwid:0  invalid crypt:0  invalid misc:0

eth0      no wireless extensions.

lspci 

00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 18)

00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 18)

00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)

00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06)

00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 06)

00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 06)

00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 2 (rev 06)
00:1c.5 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 6 (rev 06)

00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06)

00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a6)

00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC Interface Controller (rev 06)

00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 6 port SATA AHCI Controller (rev 06)

00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus Controller (rev 06)
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 Series Chipset Thermal Subsystem (rev 06)

03:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01)

04:00.0 Ethernet controller: Atheros Communications Inc. AR8152 v1.1 Fast Ethernet (rev c1)
ff:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 05)

ff:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 05)

ff:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 05)

ff:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 05)

ff:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 05)

ff:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 05)

I hope this information is of some help.