IMac 27'' mid 2011 hard disk failure with FileVault 2

Question

Hi,
Recently I had had some troubles with my iMac and everything is pointing out to the hard disk.
2 weeks ago I rebooted the iMac and i lost all my data because of a hard disk failure. The disk just got corrupted according to what i could see. From there, i had a lot of troubles trying to reinstall the last version of OS X (10.8). I indeed formated the disk and i even securely erased it. When I tried to reinstall it from external HD or from a USB key i usually (not always) got error in the final steps of installation. However, if i use the Recovery partition to install from Internet i ain't got no errors.
With OS X already installed, i also tried to encrypt the disk using FileVault 2 and i got an error again. This time, when 2 hours left to finish the encryption. Specifically this error: https://discussions.apple.com/thread/4218952?start=0&tstart=0 (Trying to encrypt but it always fails). It seems to be a common error which a lot of people is suffering, but i still don't know if my case is a hardware problem or, on the other hand, a software error.
I carried the iMac to the tech support in my city and they discarded a hardware problem. They gave format to the disk and installed OS X with no problem, so they told me to check if the iMac keep spitting some error or just it has any anomalous behavior. Actually it seems to run fine, no errors yet excepting FileVault 2, which is generating the same error.
I have always used FileVault without any kind problem (in all my macs, including this one), so could it be a Mountain Lion issue?

Answer 1

Back up all data immediately as your boot drive may be failing.
If you have more than one user account, these instructions must be carried out as an administrator.
Triple-click anywhere in the line below on this page to select it:
syslog -k Sender kernel -k Message CSeq "I/O error" | tail | open -f -a TextEdit
Copy the selected text to the Clipboard (command-C).
Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window (command-V).
The command may take a noticeable amount of time to run. Wait for a new line ending in a dollar sign (“$”) to appear.
A TextEdit window will open with the output of the command.
Normally the window will be empty. If you get output like this:
kernel[0] <Debug>: disk0s2: I/O error
the boot drive is failing, or there's some other hardware fault in the storage subsystem.