There are 2 causes for this issue:
- the glasses are not compatible with the ones required by the movie you are trying to see;
- KMPlayer is not configured correctly. In this case, simply right click the image and go to 3D settings then switch modes until the image is clearer.
Most 3D movies already have the recommended glasses specified on their DVD case. Use that information and compare it with your glasses because it's very likely possible they're not compatible.