As soon as the machine starts up you see the windows xp logo, when it starts to enter the xp environment the screen stays black and the white arrow appears, and everything just sits there.  You can move it (arrow) around but nothing works and will remain that way until you hold in the power button to shut down the syste. 

You can start in safe mode but I have not been successful in reinstalling XP in safe mode it will not accept the authorization code and it is legal. What is up with this???

Does anyone know why this happens, about 6 weeks ago anti spyware software was installed is this the problem...what can be done

thanks