> I haven't resized the partitions; they were created
> by the Ubuntu Lucid installer (alternate CD) and I haven't touched them
> since.
Wow. Then that installer is seriously buggy - this sort of thing can lead
to data loss if you're unlucky. I suggest you file a bug...
> I believe I have lvextended the home partition, but that's it.
That won't cause what you're seeing here - that's at the LV layer, not the
PV layer.
