I have a bit of an issue, and since it may be security related, I thought it best to post here to ask for advice, since I can't seem to find anything anywhere. I apologise if it's entirely unsuitable for this board but I really don't know where else to ask.
Until today, everything has seemed perfectly fine on my computer - a little slow now and then, but nothing major. However, when I went to check for a download today (from months ago), I found that there was a user account on my computer that I don't recognise. I've attached a picture of what I found. The green square is my user account, and the red one is the one in question.
The thing is, I'm the only person who uses this computer. I know this because there are only 3 of us in the house and the other two don't even know how to turn it on, let alone use it, and I also know noone by the name Matt.
The computer is never outside my house, so I know noone got ahold of it, so I'm trying to figure out where this account came from. I ran a virus scan just last night as part of my standard upkeep, and just to be certain also tested with MalwareBytes, and neither found anything suspicious, so needless to say I'm confused as to how a new account was made on my computer without my knowledge, and without anyone else being near it.
Is there any way to check if anyone has had remote access to the computer, or how the account was made/ who made it? Nothing is stored in it apparently, so i don't even know if I ought to just delete it or investigate further.
If anyone can advise me, I'd be hugely grateful, as Google has turned up nothing that seems to relate to my situation, so I have no idea where else to turn.
For reference, I'm using Windows 8, with Avast Internet Security installed and running, am on wireless internet at home, secured with 'WPA2-PSK' security (whatever that means) and, as mentioned, am the only actual user on this computer besides the unknown account.
