Here's a literal screenshot:
See "Kernel panic - not syncing: Attempting to kill init!"
Again, this isn't a boot problem; it happens while I'm using the PC, or I believe sometimes overnight. I've done a memory test and confirmed my memory is fine, so I'm wondering what to try next. Should I try a different kernel?
This is on a Lenovo T520. I can't think of any recent hardware changes that could be related.
This has apparently stopped as of kernel 3.8.0-19-generic and the updated Intel driver. Perhaps it was a bug.