Comment 19 for bug 300693

Some more searching provided this URL:

http://agiletesting.blogspot.com/2008/11/issues-with-ubuntu-810-on-lenovo-t61p.html

Cut from there:

System lock-ups with Intel 4965 wireless

The version of the iwlagn wireless driver for Intel 4965 wireless chipsets included in Linux kernel version 2.6.27 causes kernel panics when used with 802.11n or 802.11g networks. Users affected by this issue can install the linux-backports-modules-intrepid package, to install a newer version of this driver that corrects the bug. (Because the known fix requires a new version of the driver, it is not expected to be possible to include this fix in the main kernel package.)

As recommended, I did 'apt-get install backports-modules-intrepid' and I rebooted. That was around 1 hour ago, and I haven't seen any issues since. Hopefully that was it. BTW, when the Caps Lock light blinks, it means 'kernel panic'. Who knew.