Yeah, that's been mentioned before - it happens with all forums and all threads. The spanning mechanism always spans one number too high and therefore produces a blank page. This has happened since the first ever release. :-\
hmm, weird I thought Jason already fixed it. Last time I talked to him about it he said it was only a problem with the copy on gossamer. Some problem from a very long time ago.
It seems our post count got out of whack with how many posts there were in the forum. This was most likely due to the number of upgrades and beta code we've gone through. =) 1.1.4 now fixes this by automatically recalculating the count after each post.