NIS2013 Windows XP sp3

Quick and full system scans will not run on command. Have had one session on chat 2 days ago and resolved problem for one scan only. I have uninstalled run removal tool and reinstalled and first system scan will  run but then no response. Reputation scans and Facebook scans run with no problem. Have run check disc on internal and external hard drive with no results. Waited for over a half hour on chat line today without talking to anyone and yesterday could not connect to live chat. A problem detected message popped up today saying "could not run scan due to internal program error" . Live updates are working okay. My worry is if there is an internal program error is my computor protected ???????