Windows 7 Desktop slideshow issue

[Gorbash]

Ok I wouldn't exactly classify this as a major problem, more of an oddity.
I'm using Windows 7 Ultimate 64 bit.
I use the desktop slideshow feature, directed to a folder in my pictures folder that I named desktop slideshow, I have about 1000 images in there, it's set to change image once every 30 seconds.
Here is the problem, I tend to see the same 20 images or so go by over and over, and only once or twice in each loop does a new image show up, eventually I see a great number, but it tends to favor those same 20 or so images predominantly.
They don't have similar names, they are widely differing in size, dimensions, and every other aspect. But for some reason the slideshow tends to pick them to go by more than anything else. I removed the images, and it chooses another 20 or 30 seemingly at random to give priority over the rest, only slipping in a random one between those repeated choices once or twice in each loop again.

So here is my question, does anyone know what criteria or method is used to cycle the images in the desktop slideshow? The whole reason I started using it was because I like the idea of seeing any one of a thousand or more pictures on my screen when I close a window, and it's kind of nice to have something I'm working on in my main screen while random art goes by on my second monitor, but with the same images repeated, it sort of loses the appeal.

So far my only option has been to remove the over used images after a while and cycle in some of the old ones I removed before. But that's not really all that satisfying a solution.

So I would appreciate any suggestions or insight, I searched around google, talked to some friends, and generally applied my brain to the issue for a few months without any breakthrough, and decided to seek some info from this forum since it seems to be fairly chocked full of people who have considerable knowledge of the concerned operating system, big surprise considering that is the point of the forum eh?

Thanks in advance for any thoughts on the matter. I apologise if this isnt really the right place to put this post but I didnt think it quite fit in any of the other sections better than it did here.

 

[Saltgrass]

I don't really know what might cause some photos to have priority, but is there any similarity in where the photos are located in your file list? Have you put any tags, or rated any of the photos?

Have you tried changing the Picture Position in case the size or resolution is involved?

Do you have Shuffle checked?

 

[Gorbash]

I don't really know what might cause some photos to have priority, but is there any similarity in where the photos are located in your file list? Have you put any tags, or rated any of the photos?

Have you tried changing the Picture Position in case the size or resolution is involved?

Do you have Shuffle checked?

the photos position in the folder doesnt seem to have anything to do with which ones end up with priority as far as I can tell. None of them have tags or ratings either, I appreciate that suggestion, I had not thought of it, but unfortunately after checking the entire folder none of the images has a rating or tag, out of curiosity I tried rating a few of them and it didnt seem to make a difference.
Yes shuffle is checked on the desktop image preferences.
Thanks for the reply.