Purely for the reason above.
Ok, search result returns:
post 1
post 2
post 3
Refresh will only ever return those posts in that order, but WILL show the latest post by each one (which is they'll sometimes be in the wrong order).
It's basically due to this:
Get New Posts = search.php?do=getnew <-- this actually gets the search results and stores them in array X
which redirects you to:
search.php?searchid=X (where X is the post array)
So hitting F5 will only ever refresh the array, NOT get any new threads.