I Shudder When I See the Open Shutter

This one's pretty easy.

 Use 'shutter' for a thing on a window or camera that can open and close (the SHUT in SHUTTER).

 Use 'shudder' for trembling, shivering, shaking, etc.

This can be an easy typo to make--especially for those among us who write romance novels or scary stories, because there can be a lot of shuddering going on in those genres.

We get accustomed to typing 'shudder' and, the next thing we know, we've given windows and cameras the shakes.