I've got a good one.
One of my co-workers asked me to try to save his laptop. It was originally running XPee, and it would constantly reboot itself before the OS was loaded. His recovery disk failed to format the "user partition," and BartPE couldn't read the disk.
I popped a Gentoo LiveCD into the drive and was succesfully able to mount the Windows partition and read the contents of the drive. I was able to succesfully back up the previously inaccessible contents.
Here's where it gets interesting. fdisk fails to write to the partition table. I had to reboot to get out of the stream of garbage that spilled across my screen (in all 6 virtual terminals, no less!). When I switched back to X and opened a terminal, fdisk read one big linux partition. mke2fs -j just froze. I rebooted and ejected the CD, and buddy's old 'Doze install came up.
Now, I wouldn't be surprised to see 'Doze crap up the whole partition via a virus or spyware, but shouldn't I be able to blow away the partition from a bootable Linux CD? Any malware on the disk wouldn't be able to touch Linux, especially since I tried fdisking from a fresh boot without mounting the drive. Anything in the RAM would have been gone as the computer was left powered down overnight. Anything in the MBR would have been ignored because Gentoo booted directly from the CD.
That's looking to me like a damaged hard disk, but I'd like a second opinion (or better yet suggestions) before returning the computer and saying "It's pooched. Get a new one." Especially since there's a case of beer in it for me if I manage to get this fixed
EDIT: I've also tried an Ubuntu LiveCD. GParted crashed. I prefer to keep using my Gentoo disc since it doesn't take 20 minutes to boot.