There are times when you want to allow a user access to your computer and you are running password file sharing which requires any other computer connecting to yours to have an account/password on your system.  While this adds security to your local file sharing network, it would allow the user to log into your computer while at your computer and have access to it.  

To prevent a user or user group from being able to log into your system but still access files or printers remotely, you can follow these steps:

1) In your Start Menu search box (located at the bottom of your Start Menu, type 'local' and you should see the "Local Security Policy" title listed.  

2) Navigate to "Local Policy"

3) Navigate to "User Rights Assignment"

4) Locate on the right side and double click on "Deny Log on locally" (you may also want to repeat this for "Deny log on through Terminal Services" if you have that service enabled.

5) Add the user or group you wish to block from logging in locally to the list.

That should take care of it!