I turn mine off daily, but only to help lower the dust it acquires. I live in a farming community and dust is ever present.
I really dislike having to do so, because I am a believer that turning a machine off and on shortens its life span by putting temperature wear on the components
Erm. It is true that "s**t" is more likley to happen durring a boot or shut down, but tempurature isn't why.
One day my HDD decided to try out Sepuku. It didn't have a knife handy (or a towel for that matter) so it decided to stop spinning.
symptoms (for future reference to a possible solution)
*Hard Drive Not Spinning
*Bios Not Finding HDD at Boot
*Yelling, Screaming, and Killing people feels like the next logical step
There's three possible solutions (at the very least to retrieve your data)
Try First:
Problem: The discs are stuck
Solution: Shake the drive like a British nanny! Don't hit it against anything, but rotate it in your hand twisting back and forth, HARD. It should free up the discs.
Try Second:
(My)
Problem: See if other head settings will work (if your drive has the options)
If this is the case, then either the logic board has damage somewhere or became mis-aligned somehow.
Solution: Find an identical HDD (and I do mean IDENTICAL) and swap the logic boards (Requires a torx-8 screw head). Immediately buy a new HDD and either make a image of your current drive (NOT through Nero or something, but Ghost or Drive Image) and pop in the new drive install the image. OR Install whatever OS, slave the old drive and copy the files you want to keep.
If you're lucky it's still within the warranty period and taking the logic board off doesn't void the warranty (since there's no way for them to tell) and you may be able to get a replacement AND keep your data.
Try Last:
The only other option is to have your data professionally retrieved. Or, you could, somehow, get an identical HDD and swap the physical discs (not recommended) I doubt it would work in general though. But if you have a 'clean room' and no way to damage the discs (or heads for that matter) go for it!
There are two other possible problems that can occur.
The disc head's get misaligned somehow and grind into the discs:
You have to toss the HDD. There's no saving it, unless you want to spend thousands of dollars (which may not work).
The discs just funk up. (Common with Fujitsu drives, in fact, those are the only drives where I've seen the discs just stop saving, most other drives have enough replacement cylinders.)
Toss the HDD, again. There's no coming back (unless you have thousands of dollars).
So, hope this helps.
Oh and my drives pins became misaligned somehow. I re-aligned them and it works fine. I still need to replace the HDD though, just not to chance anything else happening.
Blame it on Microsoft, God does.