If a question has multiple pages of answers and the set of answers that span the page boundary have the same vote totals, when you click the next page button you might miss an answer as the random sorting order may move an answer that would have been on the succeeding page in the first ordering into a position that would now be on the preceding page.
For reference, please see this question: http://stackoverflow.com/questions/8440/visual-studio-optimizations. Notice that when you click the next page button, one (or perhaps both) answer(s) from the first page appears at the top of the second page. Presumably this slot(s) would have been filled with another answer(s) were we able to view what the page would have looked like in the previous ordering. To the user unaware of the feature, this answer(s) has been "lost." To others, it is merely painful to know if you have seen all the answers unless you refresh the page enough to be confident you've seen them all. This can be difficult if the number of answers is large (I tried to work out an algorithmic complexity bound based on probabilities for a way to be sure: I think it may be O(n2) views).