Norton opens sometime but closes when I click run scan

I thought I had a virus but I could not even open Norton to run a scan so I had to install a microsoft program to remove the virus.  Norton power eraser says I do not have a virus.  I uninstalled the microsoft program and I uninstalled norton antivirus and reinstalled it. Still norton antivirus doesnt always open but when it does I go to click scan and then it closes.  It is not working at all.  I do not know what else to do.