I have a titanium-cased Toshiba laptop I got secondhand - who the hell puts laptops inside titanium cases, anyway? This thing weighs twelve pounds, and you could probably drive a car over it when it's closed. But anyway, it has a decent 64-bit CPU, a pretty good battery life, there was room for 8 Gbytes of memory (only had 2 when I got it), and it was cheap because the screen is a semi-weird size and smaller than 1080p - it's 1024 x 1200 pixels. So I nabbed it, got the extra memory installed, (I had to buy a special Torx screwdriver with a hole in the middle of the bit to get the turtleshell off and back on) and took it home.
I had to literally remove the internal hard drive and replace it with a blank one before it would allow me to install Linux. The thing has a BIOS setting that makes it flatly refuse to commit writes to the first disk partition (where lay the boot sector and OS, in the original) unless they are signed by some trusted authority whose key I don't have (possibly the same people who put it inside the titanium turtle shell, possibly Microsoft, I dunno) and you cannot turn that BIOS setting off, even with hardware access, as long as there is a drive capable of booting up. That setting isn't even writable except after a failed boot which did not fail because you interrupted it via power cycle or keyboard.
I don't know if that's a feature of the regular Toshiba BIOS these days -- obviously the machine was built by some kind of paranoid organization, so it might have a custom BIOS installed -- but it was the first time I had run across anything like it.