Windows 2000 lockups and IE crashing

I am trying to recover a W2K pc that had numerous viruses, trojans and spyware running on it. I have run numerous programs to clean it up. At one point, I also tried recovering the OS. Now it appears the two things that still has problems with are: 1) IE cannot access ANY websites. It immediately brings up the MS IE has encountered a problem and needs to close error. If I bring it up to a blank screen, it is fine. If I try to go to a website, it bombs. 2) When I shut down, it goes through the process until the screen goes black and then hangs. I have to press in (and hold) the power button to get it to go off. Does anyone have any idea what would be causing this and what I should do to fix it? Thanks!