Comment 4 for bug 230006

Ooh, I found a great example of what could be causing this:

https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/113515

Basically, the bug is that, since /etc/lvm/lvm.conf is *not* in your initramfs, LVM defaults to scanning all devices for PV's, and locks onto the first ones it sees (which it shouldn't.)

I'm not sure whether the above bug was fixed yet or not, though. Make sure you have the changes I suggested for lvm.conf, then try updating your initramfs with:

update-initramfs -c -k `uname -r`

then reboot and try again.