Big problem anyone have any ideas?

Hey guys,

So recently I tried to download a windows 7 crack (I'm running XP) and got a few trojans, Norton picked up on that, advised me to download a program to remove one of them, i followed the instructions and restarted the computer, when I started it back up there was yet another trojan to remove, so I followed the same instructions but for a different trojan and restarted my computer...

So now when I try to start the computer, during the windows loading screen I get blue screen of death and it restarts. It just does this over and over again. On top of this for some weird reason, my keyboard doesn't work on this particular PC, I've tried it on two other laptops and it works fine, I also tested the USB ports on the infected PC with a USB fan, which worked and my mouse which lit up, so I'm assuming there's nothing wrong with the USB ports (they were also all working fine before the incident so I'm guessing this isn't just some really unlucky coincidence).

So I can't start my computer in safe mode because the keyboard doesn't work and I can't access my computer...Any suggestions on what I can do to fix this mess? Thanks.