Disk Full
I've had a cold for the past few days, so haven't checked my News Aggregator. I check it for two reasons:
1) I find interesting things there.
2) To ensure that it's still running every half hour.
Well, it hadn't run since Thursday. A little poking around discovered that the reason was because my virtual disk was full. Found 2.5 gigs to delete, and I'm back in business.