Problem with a function on a site

I need to be able to move a .gif book cover from one spot to another.
The tech folks there don’t know why I can’t do this on my computers at home.
I have an old Sony laptop, xp pro, FF, and dial up. Also, a dell desktop, xp pro, FF and dial up. I tried to do the “move” with IE and it didn’t work.
I used a computer with Ubuntu, FF, broadband and It worked.
I am ignorant about this. I am not the only one having problems with this function.
I don’t know what process the site uses to to this function. I don’t know enough to describe it better.