I noticed today that the usual arrow at the bottom left of desktop shortcuts has been replaced by the user icon of two figures (http://i.imgur.com/F3xcWAW.png). When I go into security properties, there are two user groups that I don't see in other files. One called INTERACTIVE, and the other called Account Unknown(S-1-5-21-4180935659-2234933324-3389827175-1000). Upon doing some research, it was said these unknown accounts can pop up when an account was deleted. I only created one account on this computer since I built it, my main account. I scanned with Malware Bytes, which came up clean. I am currently scanning with Bitdefender as well. Trying to delete the user results in a message describing how I can not remove it as it is inheriting permissions from it's parent, and that I would have to disable the inheritance feature in order to remove it.
Help would be appreciated.