No Pictures as Desktop background

Good morning to everybody;
My OS is W7 pro.
It's a couple of days that it is impossible to use any picture as desktop background image on the screen.
The only thing I have done before was the uninstalation of the "Offerbox" SW.
When I execute the procedure to personalize the screen and I select the desktop background, after having selected the file with the pictures I get the squares of the pictures without any image ( that is : the squares are empty).
If I look to the pictures with any picture viewer, the pictures are perfectly displyed.
Thanks in advanve for any help
frasal

To Brink:
I tryed to do this; but it does not work because it says it cannot complete cause a non answering program program.
What do you think if I try to reinstall the OS using the update function of the original W7 dvd? ( If I have correctly understoot this will allow for the saving of all my parametrizations of the System)
Thanks and regards
frasal

To Sledge DG.
I checked what you are suggesting but nothing changes. As said in my first post, when I ask for the pictures I get an image like that in your post where, for every picture, there is a blank square. ( sorry I dont know how to put my picture in the post).
In addition I discovered that in any case the system does not save my selections
Regards
frasal

Hi Brink,thanks for your courtesy.
No I have not tryed what you suggest; i will try it and inform you.
Regards
frasal

Hi Brink , I have done the System Restore at Boot and it worked very well and now the pictures problem has been fixed.
Thanks very much again and regards
frasal