I've had the same experience virtualizing Ubuntu 8.10 and 9.04 boxes ... We use lilo and xfs, I don't know what p2v does after the 97% stage, but I've found I get a functional system if I just rerun grub-install or lilo in rescue mode .. More specifically:
- hardware -> cd -> 'connect at power on' an Ubuntu install CD
- options -> advanced / boot options: Force BIOS setup
- power on, select boot in the BIOS and +++ CDROM to the top
- rescue a broken system, select correct root partition, execute a shell in it
mkdir -p /var/run/network
mkdir /var/lock
rm /etc/udev/rules.d/70-persistent-net.rules
rewrite /etc/fstab UUID entries to /dev/sda
rewrite /etc/fstab non-ext3 filesystems to ext3
lilo
sync and power down
disconnect cd