It worked fine, but after it had been switched off it absolutely refused to boot - no error messages or anything.
Went into the bios settings to take off quite boot and quick boot, but still no errors.
It booted off the Ubuntu live CD ok, and I could mount the linux root partition.
My best guess was that the boot loader was mangled, so I re-installed grub by doing:
sudo mount /dev/sda6 /mnt [sda6 is my root partition]
grub-install --root-directory=/mnt /dev/sdaThis worked ok with no errors, and re-booting the machine gave the familiar grub boot menu. Ubuntu booted ok...we'll see if it works after I use Windows next time - I suspect it was Windows that killed the boot loader!