Not sure if this is actually a hard drive problem but the symptoms involve them.
I have 6 spinning disks and one ssd in my desktop, Windows 8, the other day 2 of the drives stopped showing up in file explorer and sometimes when opening file explorer it would stop responding.
I disconnected all the drives and connected them one by one with a reboot, on the first reboot file explorer would stop responding, on a second reboot the latest connected drive would now show up and so on up until I had 4 drives connected and on the 5th the problem would come back of the latest and the drive before it (the 4th)would no longer show up.
Even with just the C drive connected file explorer will stop responding on the first boot but after a reboot all is ok
If I reboot into a Ubuntu live cd the same drives that wouldn't show up in Windows also do not show up in Ubuntu.
I tested all the drives individually in a second desktop and they are all fine.
I'm really at a loss as to what the problem could be, I don't think it's the PSU because I can still run games without any problems and it isn't ram as I did a memory check with a Ubuntu live cd.