Norton Anti-virus

Twice this last week I got a "pop-up" message from Norton Anti-Virus that they had to do a scheduled scan. Each time I stopped whatever else I was doing and let it proceed. Each time it got to a certain number of items scanned, it crashed (meaning everything started again from the beginning, and not from the point of the crash). I just got another message to start the whole thing over again. I can't help but think that the scan hit some sort of adware "trip-wire." To add to my paranoia, my computer has been getting more and more sluggish - but checks ("sweeps") reveal nothing. Should I let Norton know? If so, how?