The U.S. government has issued an urgent alert to Windows customers.
Homeland Security is telling Windows users to uninstall Apple's QuickTime program.
QuickTime is the video and audio software that at one time was widely used to play movie trailers and other internet media clips.
Apple's last QuickTime update came in late January.
But Apple decided last week not to issue any more security updates for QuickTime on Windows.
The software still works, but without support, it could increase the risks from viruses and other security threats.
U.S. government urges Windows users to uninstall QuickTime