So you've run out of space on the hard disk, you've forced a shutdown at various times and you've overclocked the PC! It's hardly surprising you've got a few problems. I presume you were using Norton GoBack to try and put things right. I would guess that if you haven't got enough disk space to run Defrag, you won't have enough for Goback either. My normal reaction would be do delete all the existing partitions, format the hard disk and start over but I presume you don't want to do that.
Can you start your PC in Safe Mode?
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.