I'm running Ubuntu 11.04 in a dual-boot with Windows on a Dell Inspiron N4010 (kernel: 2.6.38-11-generic-pae). Sometimes (about half the time as far as I can tell), when I boot Ubuntu, the network manager refuses to acknowledge that there are available wifi networks. I've made sure both "wireless" and "networking" are enabled. I've even stopped the network manager process, deleted the NetworkManager.state file, and restarted it to no avail. It still says there are no available networks. And yes, there are available networks because they're there when I boot into Windows.
This same pattern will repeat the next couple times I reboot, then I'll give up. After a while, I'll boot Ubuntu again, and everything's hunky dory. Network Manager starts, sees my default network and connects.
The most frustrating thing is when I booted just now to gather information like lspci, dmesg, etc., it worked with no problem. I'll post the current lshw output now, and later when it decides to not work again, I'll post lshw again for comparison.
Thanks for your help.
description: Wireless interface
product: BCM4313 802.11b/g/n Wireless LAN Controller
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:04:00.0
logical name: eth1
width: 64 bits
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=wl0 driverversion=126.96.36.199 ip=188.8.131.52 latency=0 multicast=yes wireless=IEEE 802.11
resources: irq:17 memory:f0300000-f0303fff