I notice that at time I am unable to click for the next page and there are more pages available. I get "vBulletin Message Sorry - no matches. please try some different terms." This happen when I am in "search forums-search-new post"
I just had this happen to me as well. Change your settings for how many posts you want to see per page (I'm set to 40)....I had to change to 30 temporarily until the thread went beyond the page I was having an issue with.