Since migrating to 12.04 (though I'm not sure this was the cause), I've been having repeated instances of my computer reporting that my root partition is full. (20 GB, separate from /home and /boot) Reports first when under a gigabyte, then if left will eventually completely fill.
I can't find any specific set of actions that would cause this--it often seems to happen first thing in the morning, after the computer has sat for a while, though not exclusively so. When full, functionality is reduced (some things won't load), though stability remains.
Rebooting the computer seems to clear out whatever it is, and resets to normal, where / isn't even close to full.
I've dug around with an elevated nautilus window and the disk analyzer, thinking this might be some error logging problem, but I can't find anything, despite several searches. Can someone give me some direction on this? I'm at a loss.