trojan horse attack

Yesterday I had to reinstall my hard disc, of my computer.
A program refused to function, due to my own mistake,
and I decided to clean the whole thing out.
After reinstalling my C-disc, updating all virusses and what more,
suddenly my computer froze into a panic, and nothing worked anymore.
even not Ctr-alt-del buttons...!

I unplugged the power..and fortunately the thing defrosted.
Norton made a comment that he had spotted a trojan horse attack! ,
he had to take his breath again, and fiercely put the horse under fire!

Then after an hour or so...Another attack happened..again the whole thing frozen.
nothing but.... all dead...and freezing.
Again Norton announced a second failed attempt of a Trojan horse.
who was hijacking, stalking my computer!

pffft...!!!!!!!!!