Doomed to fail...

Whenever I boot a computer from cold, I'm always slightly nervy until the OS had loaded, this is probably from the number of times seemingly OK equipment has just coughed up blood. Well, today was the debut of my laptop HD problem... The BIOS fails to detect the drive, so it spits out the immortal words "Operating System Not Found". So I reboot, get same message... reboot again, tada! It's "working" again. I have a recent backup(yesterday evening), so data loss isn't a problem, instead merely just the inconvenience of being without my laptop. Curious about what state the HD is actually in, I ran ScanDisk, which returned no errors, and I ran a SMART viewer, which also said the drive was fine.. I'm stumped.