Computer freezes upon bringing wireless interface up

Question

I installed a new wireless card in my laptop, replacing a Broadcom 4312 with an Intel 6200 wireless card. Now, whenever I bring the interface up with ifconfig wlan0 up, it freezes. I'm running Arch Linux, but my Ubuntu 10.10 boot media freezes during boot if my wireless is switched on (hardware switch on my laptop). If the hardware switch is in the "off" position, it boots normally and behaves normally in the desktop environment. If I switch the wireless switch on at that point, it freezes immediately.

This happens whether I have X running or not. If I'm using the tty framebuffer in runlevel 3, the blinking cursor stops blinking when it freezes. Sometimes it actually completes the command ifconfig wlan0 up and gives me another prompt, but it will freeze within a few milliseconds after that. If I'm in X (whether GNOME or KDE), everything freezes and I lose the ability to control the mouse. The screen freezes, and whatever sound is playing at the moment will skip indefinitely like a scratched CD. If the mouse is an animated cursor (the "busy" or "waiting" cursor), the animation freezes as well. CTRL+ALT+Backspace does nothing, nor does ALT+PrntScr+K. I have to hard power down at that point by holding down the power button.

I'm running kernel 2.6.36, and I see the appropriate firmware in /lib/firmware (iwlwifi-6000-4.ucode), as well as the appropriate kernel modules (iwlagn,iwlcore,mac80211,cfg80211). ifconfig -a shows the appropriate interface with the correct information regarding make/model/MAC address, and iwconfig shows the right interface as well.

I don't have access to Windows, but I do not think that it is necessarily a linux-specific problem, since it looks like other people have had similar issues in different operating systems.

Anyone have any ideas how to troubleshoot this?