I assume that all of the trouble machines that are automatically connecting are using Intel PROSet Wireless Tools. Simple fix.
Goto the Control Panel.
Type Wireless in the search panel.
If Intel PROSet Wireless Tools is an option click it (if not then you may have another issue)
Under the option Intel Wifi HotSpot Assistant click Settings
Uncheck Automatically Connect to free WiFi Hotspots.
Click Close
Your DONE!
Problem Solved Unless you are not using Intel PROSet Wireless Tools.