I realised now, though, that it's not a hardware problem, but that of software… Microcrap Windows, to be exact. I ordered a new HDD and will be installing a fresh new, erm, installation of Winblows there. Then, if I'm still lucky, I can retrieve the data from my old C: drive and throw it out the window afterwards.
On another note: HARRY POTTER AND THE HALF-BLOOD PRINCE will be released tomorrow! HOOAH!