You can disable the setting that prevents your PC from booting, in the BIOS. I can't remember where exactly. I had a problem with one of my hdds a few months back, and it's still working. I just had to disable that setting in my BIOS to boot. Then you can at least back it up in case it fails.
That's the S.M.A.R.T system doing its thing. It's advising you that your Hitachi Hard Drive is showing signs that can lead to a failure of the drive. I'd replace that sucker ASAP.