Comment 39 for bug 548992

This is also happening on my laptop after an upgrade from Karmic to Lucid. Symptoms are the exact same as reported by original poster. Laptop is a Dell Latitude D630 with Intel wireless running kernel 2.6.32-24-generic. Output from lspci:

0c:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection (rev 02)
 Subsystem: Intel Corporation Device 1020
 Flags: bus master, fast devsel, latency 0, IRQ 28
 Memory at fe8ff000 (32-bit, non-prefetchable) [size=4K]
 Capabilities: [c8] Power Management version 2
 Capabilities: [d0] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
 Capabilities: [e0] Express Legacy Endpoint, MSI 00
 Capabilities: [100] Advanced Error Reporting <?>
 Capabilities: [140] Device Serial Number ea-13-a2-ff-ff-3c-1f-00
 Kernel driver in use: iwl3945
 Kernel modules: iwl3945

I can confirm that the fix for me was also to remove network-manager and then install wicd in it's place. My wireless connections seem to be working now. I have to believe this bug is affecting a very large number of users.