Why Did a Windows Desktop Briefly Appear on My Nan’s Smart TV?

I wouldn’t assume the TV was hacked based on this alone. Since the desktop appeared during an existing interference problem and then disappeared when the picture returned, a fault somewhere in the broadcast or video chain is just as plausible as casting. Note which input and channel were active, and check the TV’s device list and software updates if it happens again.

The repeated freezing, black screen, and audio dropouts point more generally to a signal or equipment problem. The TV may have switched inputs briefly, crashed, or displayed a frame from another connected source while recovering. Check the HDMI cables, source box, antenna or cable connection, and whether the problem happens on every channel or input.

Accidental casting or screen mirroring is one possibility, especially if the TV supports Miracast or a similar feature. Miracast can sometimes work without both devices being on the same home network. Check the TV’s connection, screen-mirroring, and device-permission settings, then remove any remembered devices or disable casting if it isn’t needed.

If the TV was receiving a local broadcast or cable channel, the desktop might have been part of the broadcaster’s equipment. Some local stations and information channels are operated from ordinary computers, so a technical fault or restart can briefly expose the computer screen. That would not necessarily mean anyone connected to the TV.