I need to reinstall Norton Antivirus (I think)

Hi, My sisters computer was full of virus after paying someone to remove them.  She tried to install Norton Antivirus

from a purchased CD but didn't know to uninstall previous anti virus which would not even open.  The Norton Antivirus finally installed after I had her remove the other antivirus in add/remove programs.  We were on the phone during this time and she conveyed the virus was really making it difficult to perform steps.  She was finally able to reboot into safe mode and perform a full system scan. During the scan she said a window came up saying she needed to re install Norton Antivirus.  We ignored the notification until after a complete scan because she had no internet connection and I wasn't sure what she could do in safe mode.  The Norton scan reported 13 virus, trojans, downloaders, etc. and reported fully resolved.  We then went through some folders and files looking for suspicious items.  

  She then rebooted and a day later reports everything is fine and running better than it has in a long time. Her Norton updates is reporting that it has been updating.  She is very pleased that Norton could manage this.

 

 I am however concerned with the pop up she received while performing the initial full system scan in safe mode stating she needed to reinstall her Norton product.  She has received no other messages after leaving safe mode 36 hours ago. I want to be sure her Norton product is protecting her computer without causing her un necessary concern after her week long ordeal with the virus and failed removal by paid technician. Should I forget about it or is there something we need to do further?  I was thinking to tell her to click on the help and support  1 click. Would that reveal any installation issues?  Thanks, she is several hundred miles from me so I can't see her computer.

Keith