Just got caught again by this LABEL nonsense. I was mounting my laptop hard disk on my desktop - both running Fedora- and the whole thing was thrown into confusion because there were two partitions LABELed "/", on my desktop hard disk and on the laptop hard disk.
I had to start again in single mode, and change all the entries in /etc/fstab and /etc/grub.conf .
Who thought up this LABEL business? It seems to me to cause much more trouble than any help it gives.