Switching between result pages doesn't work without browser cache refresh

I have a nasty problem with the display of the search result pages of my YaCY instance

Switching between the pages with search-results, does not always work correctly without refreshing the browsercache.

There is a wordkaround: With the Firefox-client I have to press F5, shortly after I click on the page numbers below the search result page. If I don’t press on F5, the same page will load again, instead of a new one.
The problem doesn’t appear to exist with seamonkey.

Because my search portal, alterlook.org is used by many external users, mostly wit firefox clients, I would very much like to solve this for all browsers. Is there a way?

Thanks a lot!