Windows XP : Splash Screen Freeze

Recently my computer was infected by the 'Spy Sheriff' hack/virus etc..I followed this guide at this website: http://www.bleepingcomputer.com/forums/index.php?showtopic=22402&pid=130094&st=0&#entry130094

Now - I was told to complete Point 15 and onwards, to which I did and rebooted the computer. I

But now, when the logging screen comes on (When you chose a user to log on as) - it doesn't even come up, it stays on the Blue/Dark Blue screen with the Windows logo and the writing 'Windows is starting up..' - it freezes at that and nothing else happens.

I think it may have something to do with merging the smitfraud.reg file that it says on the website - I'm not really sure. The VERY last option would be to reboot, as I have some very important work files I do not wish to lose.

Any help would be very much appreciated..!

 

Just to add - I can't get onto any usernames so I can't download anything..!