Update:- No further forward. I cannot boot from, or gain access to, the hard drive. As I said, the Bitdefender rescue disc scanned and removed the virus/trojans that are PROBABLY the cause, but the hard drive still won't work.
If it is the kazy virus to blame, maybe I need another way to get rid of it. There is supposed to be a removal tool available, but I don't know how to actually get it to the hard drive.
Btw, is there any way I can just format the hard drive? I wouldn't mind wiping it and starting from scratch. Unfortunately, whatever the Administrator Password was is long gone, so I haven't been able to use the Windows XP product recovery CD-ROM.
I actually comtemplated buying a new desktop PC earlier on, but I've decided to stick with this one.