Dying HDD..?

Do a SMART selfcheck or check the event logs Windows produces and search them for error on the physical drives.

Jam it back in, in the dark.

Defragmentation doesn't reduce drive capacity Zergrinch. Winter Storm should better check the reallocated sector count. If the drive is really loosing sectors the count should be quite high.

There's nowhere I can't reach.

What is "volume count"? What app do you use to extract the SMART readings from the harddrive? SpeedFan is quite good for windows, smartmontools should be used on *nix operating systems.
Can you supply the SMART readings? Would be best including the RAW data values. Are there any "pending sectors"?

You should start using the drive in read-only mode if you're not sure about the damage state. Or don't use it at all. Get a new drive fast and transfer the intact data to it. Or transfer your files to another system, maybe your friend can backup your files on his system for some time.

Keep in mind that defective sector count, caused by a crashes head on the platter, can increase because of loose particles in the harddrive box (which in turn destroy other sectors, it's like having sand in your drive).

This thing is sticky, and I don't like it. I don't appreciate it.

SMART can't always register mechanical problems, maybe the servo is failing but your hd vendor doesn't use sensors there to register problems.

And you're right. The SMART readout is fine. I would be cautious however. Higher noise than usual could be a sign of the drive failing in the near future. Make sure to have some backups if the drive fails.

I am a dolphin, do you want me on your body?