Quote Originally Posted by DLS View Post
I exported in 100% quality JPEG (aroung 7 MB I think).
That's probably your problem. The software that Windows uses to display images on the desktop does a very poor job of resizing images. First use a good resizing program (or at least a mediocre one, like Lightroom) to resize the image down to the size of your desktop. Then set the resized image as your desktop background.