I had a problem like that. I think it'S because of the browser. It solved when I cleaned cache, cokies ect.
Strange thing mate, anyone got any reason behind it? Would like to know about it, cause i have heard it first time as well, really astonishing.
if you're using firefox, it could be one of the addons you have. Also firefox has an inbuilt feature if set (and certain addons enable it including fasterfox, and some versions of adblock plus) where it navigates through several links on the page and caches them in case you visit it. It does this if you idle on a page for a bit (anywhere from few seconds to minutes depending on your settings). You could quite possibly have this enabled, maybe not by choice but an addon is doing it for you - so even though you don't click the link, it's still navigating to those pages. Just my 2 cents.