I have done some testing on your site and this is not the result that I get when I use IE 8 or any other browser.
In my first search I looked for 'bor' and found 53 results. For my follow up test I went to the search page and looked for 'ter' and this found 166 results. When I examine the URL in both of these cases I can see the search parameter present and set to search.
I'm including some screen shots from my test for your reference. It seems that there may be something else to this as I'm not getting the same result when I test it.