Norton Power Eraser scan has slowed my Vista computer :-(

I have run the Norton Power Eraser and it has now slowed my computer down so much that it takes 30mins to connect to the internet.

I did read that you can reverse the Eraser just in case it removes something important but I cannot find how to do this so that I can restore the PC to what it was like beforehand to see if that helps.

 

Any ideas would be welcome. Thank you.