I've got a Dell precision with Kubuntu 9.10. Wifi worked fine on that machine for months, but stopped working last week. I don't know what happened, but I recently did an "apt-get dist-upgrade". That might have something to do with it.

Does anyone have any suggestions that might point me towards a solution?
When I boot in Windows, wifi works fine.

Code:
tijl@Smaug:~$ sudo lshw -C network
  *-network
       description: Ethernet interface
       product: 82567LM Gigabit Network Connection
       vendor: Intel Corporation
       physical id: 19
       bus info: pci@0000:00:19.0
       logical name: eth0
       version: 03
       serial: 00:24:e8:da:e6:90
       size: 100MB/s
       capacity: 1GB/s
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=1.0.2-k2 duplex=full firmware=1.7-7 ip=192.168.0.106 latency=0 link=yes multicast=yes port=twisted pair speed=100MB/s
       resources: irq:30 memory:f6fe0000-f6ffffff memory:f6fdb000-f6fdbfff ioport:efe0(size=32)
  *-network DISABLED
       description: Wireless interface
       product: Wireless WiFi Link 5100
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:0c:00.0
       logical name: wmaster0
       version: 00
       serial: 00:24:d6:2e:ae:7a
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list logical ethernet physical wireless
       configuration: broadcast=yes driver=iwlagn latency=0 multicast=yes wireless=IEEE 802.11abgn
       resources: irq:31 memory:f1ffe000-f1ffffff
Code:
tijl@Smaug:~$ lsmod | grep iwlagn
iwlagn                124896  0
iwlcore               133600  1 iwlagn
mac80211              210040  2 iwlagn,iwlcore
cfg80211              109144  3 iwlagn,iwlcore,mac80211
Code:
tijl@Smaug:~$ dmesg | grep iwlagn
[   25.271384] iwlagn: Intel(R) Wireless WiFi Link AGN driver for Linux, 1.3.27k
[   25.271386] iwlagn: Copyright(c) 2003-2009 Intel Corporation
[   25.271706] iwlagn 0000:0c:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
[   25.271732] iwlagn 0000:0c:00.0: setting latency timer to 64
[   25.271808] iwlagn 0000:0c:00.0: Detected Intel Wireless WiFi Link 5100AGN REV=0x54
[   25.310856] iwlagn 0000:0c:00.0: Tunable channels: 13 802.11bg, 24 802.11a channels
[   25.310932] iwlagn 0000:0c:00.0: irq 31 for MSI/MSI-X
[78266.652117] iwlagn 0000:0c:00.0: restoring config space at offset 0xf (was 0x100, writing 0x10a)
[78266.652159] iwlagn 0000:0c:00.0: restoring config space at offset 0x4 (was 0x4, writing 0xf1ffe004)
[78266.652169] iwlagn 0000:0c:00.0: restoring config space at offset 0x3 (was 0x0, writing 0x10)
[78266.652181] iwlagn 0000:0c:00.0: restoring config space at offset 0x1 (was 0x100000, writing 0x100106)