Ok, I've no idea why this worked. Removed more stuff from the NTFS partition, tried again, failed again, removed another wee little program, tried again, it worked. So there I am now with my hands full of new partitions, a Debian install and no network connection - doh! But that's a story for a different thread (the very fact that you're reading this shows that my dual-boot works ). Just to tell you that it may be worth persevering. Qtparted is a wonderful program, I lost no data at all. Who needs PM? (I still did get the "labels" error message, and I had to hd-install about a zillion times, but qtparted worked absolutely fine.)