So I was minding my own business, working on my English term paper, and my Lifebook froze. So after fruitlessly trying to Ctrl + Alt + Backspace, I simply reboot via the on/off switch. After turning it back on, I got the ominous "Operating System not found" message. I tried messing with the BIOS settings; I ended up restoring to default, and still the same problem. I'm posting this from my desktop.

Any help would be appreciated!

I had that problem with the HTPC once. Let it cool down for a while, then try starting it again. If it boots, have it run CHKDSK. (Or, if you have or can obtain a laptop to desktop drive adapter, scan it with your desktop.)

Well, I tried it after an hour of it cooling, and it works. Is there anything I can do to prevent this in the future, or is it just a goofy random problem?

no, your hard drive is likely failing, and cooling caused the drive to expand ever-so-slightly, allowing the heads to move again. Back up all of your data, now. Now! This may happen again, and be fatal.

Backing up as I type this.