Some of my photos are displayed in a sort of low resolution!
I have downloaded and installed Windows Live Photo Gallery and use its screen-saver in Pan and zoom with medium speed. Many photos are excellently displayed but some are displayed in a very coarse resolution. These photos are displayed normally in other applications.
One for example is 4,15 MB width 10066 pixs and height 2619 pixs ( a panorama). I have tried to re-sample to a smaler size but the problem remains.
Using the Google screensaver they display normally, but I like the pan effect in Live Photo Gallery better.