WLAN disconnects. Every now and then.
Sometimes every hour, sometimes every 5 minutes.

Log:
Microcode SW error detected. Restarting 0x82000000.
Firmware version: 228.61.2.24

I had the problem with Ubuntu 9.10 (Karmic Koala)
and with Ubuntu 10.10 (Maverick Meerkat), too.
Maybe there’s a problem with the driver and the hardware encryption of the chipset?

And because I never want to search for this again, here’s what did it for me:

Create /etc/modprobe.d/iwlagn.conf with this content:
options iwlagn swcrypto=1

Reboot -> no more problems : )

Found at: Ubuntu Forum Community