James:

The software is Debian Sid. I had this problem, dist-upgraded and it still occurs. I am inside X when the crash happens, I have not tried closing X down for the day to see if it repeats. I am running kernel 2.4.17, and whilst I did have crashes in previous kernels (I jumped from .13) they were not daily.

Summary of what I said on IRC: If you're tracking sid closely, you should be talking to Debian lists to cure this. If they coincided with the kernel change, try another kernel.

Doubt that helped, but there you have it: replace bits until it stops crashing. Slow, tedious, but will work eventually.