When you say a "hardware fault" do you mean the hard drive as that is now the only piece of hardware I have on the computer. Since it crashed last night I haven't bothered to try and load the drivers for my printers, because previously every time I tried to load the printer drivers the computer really went gaggar.
Could my computer man's copy of XP be faulty?

When I say 'a hardware fault' I mean any part of your computer's hardware, not just peripheral devices attached to the motherboard, but possibly a fault with the motherboard itself or even the power supply giving a faulty or spiky voltage.

It's almost impossible that it's to do with the copy of XP.  The only way it could be software related is if you have re-loaded a faulty piece of software or re-infected your 'puter with a virus. That could conceivably happened when you reconnected your usb drive, but you'd probably have had to run something off the usb drive for that to happen.