I've got Win 7 Home Premium on an old laptop. I presume that Pro will work the same way - Press Ctrl + Alt + Delete and you should be presented with a screen that includes a clickable link to start Task Manager. If that allows Task Manager to open, check for any AV/anti-malware or other programs that could be slowing everything down by doing bootup AV scan(s) (or updating, defragging, etc.) Also, check for anything running that you don't recognize.

Or, just leave your computer on all day to see if anything completes and returns control to you.

Jim.