Sometimes I write a post and it just can't be seen until some other mates write other posts in that thread. It always seem to happen when a page is ending.
For instance, here,
http://www.liverpoolfc-newkit.co.uk/viewtopic.php?t=19047&start=20&hilit=new
My post can't be seen right now.
Perhaps is it related with the adverts? if the system has a fixed height and waits until a number of lines are filled by the posters to make a new page, it won't change until that amount of lines is reached. But if you place the adverts within, perhaps the system isn't counting the space that those adverts take, thus "hiding" the last posts of each page until the proper number of lines are reached.
If so, I guess it's a matter of configuring it. Just a theory.