A final post on what happened to my computer. There is some repetition of earlier posts, but I thought I may as well just write the whole story.
After the panic about the hard drive dying, I tried out a couple of other disks. At first they seemed to work, but the next day they started displaying the same symptoms as the old hdd (the one presumed to have broken). This gave me cause to believe that it wasn’t the hard disk that was the cause of the problem. At the same time as I realised this, I noticed that the DVD drive started to repeatedly make the noise it makes when it is first powered up. It seemed like the drive was being repeatedly power-cycled. I put an ear up to the hard disk in the machine; it also seemed to be whirring up and down — similarly power-cycle-esque.
This led me to the next suspect: the PSU (power supply unit). On sourcing a spare PSU from one of my friends, I was pleased to discover that the hard disks I was using to test the system were again working. Now came the moment of truth: trying out the old (presumed dead) disk. I must say that when it seemed to work and my old system appeared before my eyes, I was incredibly happy!
So in the end it seems that it was just the PSU that went bad. I finally got around to ordering a CD writer along with the new PSU, so I can burn the things that I want to save onto CD. Hopefully this will reduce panicking when the hard disk does decide to die, as it has to eventually.
All in all, an interesting — and worrying, it has to be said — exercise in my PC what’s-gone-wrong detective skills. Fortunately nothing exceptionally bad seems to have come of it (aside from the price of a new PSU). Time to cross my fingers that the system carries on chugging along…