http://www.neowin.net/news/anti-virus-software-is-locking-users-out-of-windows-8
Antivirus software packages can be an excellent PC companion to keep your machine safe and free of malware. Unfortunately, sometimes, these software packages can also turn against the user if an improper update is pushed out or if it improperly detects safe files as malicious.
If you are using Windows 8 and also have older version Webroot’s antivirus software, it’s imperative that you update to version 8.0.2.79 immediately. As noted on the Microsoft Answer forums, Webroot’s antivirus software prior to the version number mentioned above “mistakenly removes core Windows 8 operating system registry entries required for Microsoft account sign in“.
What happens if you don’t update your copy of the software? You won’t be able to login using your Microsoft account on Windows 8.
If you only sign into your computer with Microsoft accounts, and they all return the ‘password is incorrect’ error, you will need to reset or restore your computer to a point prior to Webroot being installed in order to sign in to update Webroot.
If this is an issue you are currently experience, you can hit the source link below to follow the directions to try and regain access to your machine.