Image to Desktop problem

I can no longer place an image on my desktop
. In display properties/desktop I can browse to the image and find it but it will not display in the preview window nor appear in the list
.
I can however place the image on the desktop by right clicking and selecting set as desktop, but the automatics kick in and stretch or tile it which is no good.
I have also now discovered that I can't view as slideshow, the first image in the folder displays but it will go no further. I think these 2 problems are definately related.
Any ideas?



I can however place the image on the desktop by right clicking and selecting set as desktop, but the automatics kick in and stretch or tile it which is no good.
I have also now discovered that I can't view as slideshow, the first image in the folder displays but it will go no further. I think these 2 problems are definately related.
Any ideas?