Linux – Can’t Reset Password – Ubuntu 10.04 on Hyper-V

For anybody else who ends up suffering the error 15 grief that I did, it turns out that the device naming scheme in grub (hd0, hd1, hd2...) ended up being different between when grub boots and when grub is running after the system is up and running. I spent a week with root (hd2,0) because that's what grub told me the drive I wanted was called. But when I dropped to the grub shell on bootup I was surprised to find out that what was hd2 when the machine is up, is hd1 on boot. So I changed the menu.lst to use root (hd1,0) and it started working. I hope to save somebody else lots of hair pulling with that one.

Have you installed the Linux Integration Component? SMB should work even without them, but if you're running into issues like you described, it's likely from not having an enlightened Linux install.