How can I detect whether I have been hacked, and if I have, how can I remove the threat.

MigWiz: http://www.processlibrary.com/directory/files/migwiz/28336/

File and settings Transfer Wizard

I don't know that I'd suspect someone has "hacked" your system, but it could well be compromised by malware.

You've not specified what security software you are running, but have selected Windows 8. Are you using Windows Defender on Windows 8 as your security? is this an upgrade from an earlier version of Windows or a fairly new PC that came with Windows 8 installed? Are you the only user on the PC?

Try Hitman Pro Trial Version: http://www.surfright.nl/en/hitmanpro This program may be run from a flash drive. You may need to run it in Safe Mode or Safe Mode With Networking.

And/or

Try TDSS Killer: http://www.bleepingcomputer.com/virus-removal/remove-tdss-tdl3-alureon-rootkit-using-tdsskiller TDSS Killer may be run from a flash drive. You may need to run it in Safe Mode or Safe Mode With Networking.

You may wish to download (on an uninfected PC) one or more of the following rescue scanners to create bootable media to scan the infected PC (list courtesy of forum member, GreginMich):

http://windows.microsoft.com/en-US/windows/what-is-windows-defender-offline

http://support.kaspersky.com/viruses/rescuedisk?level=2

http://www.f-secure.com/en\_EMEA-Labs/security-threats/tools/rescue-cd/

http://www.bitdefender.com/support/How-to-create-a-BitDefender-Rescue-CD-627.html

http://www.avira.com/en/support-download-avira-antivir-rescue-system

http://www.avg.com/us-en/avg-rescue-cd-download

http://www.freedrweb.com/livecd/

http://www.superantispyware.com/portablescanner.html

http://support.kaspersky.com/faq/?qid=208283363

Each rescue scanner will miss things – because none of them will have a perfectly complete and up-to-date set of definitions; so you might need to use several of these rescue scanners, or something like the Shardana Antivirus Rescue Disk Utility, which creates a custom bootable CD or flash drive that includes multiple rescue scanners:

http://www.sarducd.it/

You can also  start here - https://support.microsoftsecurityessentials.com/ and select the link that says - I think my computer is infected. Options will vary by region, but phone support leads you to Microsoft Answer Desk (http://www.answerdesk.com/) in the US at this time. After an initial free consultation, a fee will be charged for assistance, based on the details of the case.

This web site - http://www.bleepingcomputer.com- contains details for many of the common infections, often immediately after they began to appear in the wild, and instructions are provided for how to remove the infections using their malware removal guides. They also have forums where you can seek help from people who specialize in malware removal.

This may also be helpful - How to get rid of malware:

http://answers.microsoft.com/en-us/windows/forum/windows\_vista-security/how-to-get-rid-of-malware/ba80504b-61f1-4d71-960f-b561798b7b42

-steve

Thank you very much.  I thought that those were maybe templates, but I cannot see the other account, which now has mysteriously disappeared from the all accounts page where I sign in.  No, this is not where I saw the extra users originally.  Thank you for your help.  I will post if anything more helpful comes up.

I believe (my opinion) that Windows Defender on Windows 8 is superior to any 3rd party product for protection.

I'd go ahead and try some utilities to check for the possibility of infection. Since the PC is fully functional, downloading one or more of the rescue scanners and creating a boot disc on this PC is also a reasonable avenue to try.

-steve

Maybe you can try free antispyware softwares (like SUPERAntiSpyware(Free) and others) and anti keylogger software (see http://freeware.wikia.com/wiki/Lists_of_freeware_antikeyloggers) to remove any spy program or any keylogger in your system.

I am using Windows Defender.  I check for Windows updates twice daily, and all other updates, Visual Studio, HP, Windows Store, NVidia, Desktop Skype, Adobe Reader and Flash, Comodo Dragon, and Office 2013, daily.  I had not installed anything between when I didn't have the migwiz and when I did.  I am the only user; I have two Admin accounts and one standard account.  Family members are also allowed to do web searches and use some Windows apps under supervision.  I have been on Bleeping Computer, but I did not wish to install anything from them as other places said that those softwares were harder to remove than malware.  I got my computer wish Windows 8; it is not an upgrade.  I do not have access to a second PC - my family has one Apple and one Windows computer.  The Apple is the families, and the Windows is mine because I needed it for college.  I will look into the Bleeping Computer website and maybe try Kaspersky.  What do you think about the free Comodo internet security software that includes a full scanner?  I thought maybe it was a hacker because everything is so surreptitious and keeps recurring in different places.  Thank you for your response.  I will look into these other solutions you directed me to.