I don't have too much advice to help this; there's only one thing I can think of that possibly could
help. You said, "...only to say that maybe there was not the right electrical currant in the house...," correct? Do you think this may still be a problem? Check on the back of your power supply. There should be a switch (on both the power supplies I've ordered, it's been red) that says a number, either 115 or 230. Now for me, I have to set that at 115, because that's what the voltage of the power sockets in my house are. If I set it to 230 though (did it by accident once
) my computer won't even boot. If I remember right, the power outlets in England are 240 volts, so I guess you'd have to have that at 230, unless there's a 240 option. If it's on 115 right now, someone confirm this before trying, but it would be my advice to switch it over.
This is just one possible solution, and if it's not the problem, sorry for putting you through the agony of reading it all. About your hard drive...I don't really know much to do about that, sorry. Just those maintenance options that mr mixx suggested, if you're able.