live-premount fails on ext4 partition

[Rob Owens <rowens@ptd.net>]

I have a Lenny live persistent system which I use on several different
laptops.  One laptop just got re-installed and has an ext4 partition.
For some reason, I can't boot with persistence on this laptop anymore.
I get a message from live-premount stating that /dev/hdc3 could not be
mounted.

Any idea why this is?  I'm not really sure why it's trying to mount the
hard drive at all, unless it's looking for a persistence file (but I
have a live-rw partition on the USB).

-Rob