Vulnerabilities in Windows and Mac OS are discovered all the time. Microsoft and Apple release critical updates (patches) to remove these vulnerabilities. It is important for you to allow these updates to install, and also to check occasionally to be sure you are receiving them correctly.
Please verify your Windows computer is up to date:
Click on the Start menu: All Programs: Windows Update
Click on the Start menu: Click the Settings (gear) icon: Update and Security
From the Apple menu choose App Store: Click the Updates tab: Look for macOS updates.