I have been too lazy to copy the exact kernel error down by hand. There's a lot of little numbers there.
But, I noticed that the error had to do with a serial module. In my past wrestling with the IrDA setup trying to get it to work, I read some things about the X40 and serial port issues---something like the IrDA won't work unless some serial port module is compiled as a module and not into the kernel.
I remembered that one of the packages that had been updated recently was irda-utils.
So, I rmmod'ed all of the IrDA modules. Haven't had the kernel bug come up since. Guess that must be it.
This is with kernel 2.6.10.
EDIT: I rebooted today, and this time, instead of rmmod'ing all of the modules, I just stopped the irda-utils services with /etc/init.d/irda-utils stop. So far this also seems to be working.