Quoting Arjen Lentz (arjen@lentz.com.au):
*sigh*
I have a true story though - had an issue with a Shuttle mainboard LAN port not working properly. [...]
One way to discourage this sort of nonsense in advance: # dd if=/dev/sda of=bootsector.img bs=512 count=1 # dd if=/dev/zero of=/dev/sda bs=512 count=1 Store a copy of bootsector.img somewhere safe. Bring unit in for warranty service. If they try to boot it, say 'I've wiped the hard drive, as it has sensitive data that I am not allowed to disclose.' WIth reasonable luck, they will not insist on installing an OS for some wacky reason. (If they do, you have backups, right?) Assuming they don't reinstall the hard drive, when you take the unit back, you can just dd bootsector.img back, reboot, and you're back in business. The shop doesn't even know Linux was there all along. Of course, putting a spare HD into the unit would also do.