You can't remove a VG because the system says that it already exist, but if you execute a vgscan you can't find it.
Delete the correspondig entry in /etc/lvmtab.
Delete the correspondig device calling
rm -r /dev/GROUP
The combination of kmod and modprobe as generated a loop.
The element CONFIG_UNIX must be part as the kernel (set to "y") and not loaded as module.
Unable to create the required files if /tmp is mounted as tmpfs.
Don't mount /tmp so that it will be physically in the root partition.
Mount /tmp in a physical partition instead of in the RAM.
Don't forget to restore your original configuration, if you want.