PC users are being urged to upgrade to the latest version of Windows 10 to fix a security vulnerability in the wallpaper system.
Microsoft says the issue has been fixed in version 1709.
That means users who already have the software installed should be able to upgrade.
The company is also making a special offer to users who buy the upgrade for $100, which includes a $100 discount on any new Windows 10 system.
The new wallpaper system in Windows 10 can only be accessed through the Windows 10 Start menu, so users will have to find it by going to Settings, General, and then clicking on My Settings.