Please help! Unknown msert[1].exe download message

Hello. This morning while I was on the Internet, right after a started a full system scan, I noticed a pop-up from Norton that notified me of download scan results, telling me that msert[1].exe is safe. I know it's somehow related to Microsoft Safety Scanner, but I didn't download it today. I downloaded it a couple days ago, but not today. When I checked "More Details", it mentioned it was downloaded from Microsoft, but it also said "fewer than 5 users in the Norton Community have used this file" and it was released less than a week ago. While I was checking this out, I noticed our Internet connection briefly shut down, then started up again. Is there something wrong and if so, what should I do? Thanks.