ok, actually the bug is a little bit different. I had my thread preferences set to display 10 posts per page. My 500 error post just happened to be the 10th post (not counting the sticky post) at the time. So, as long as I had my preferences set to 10 posts displayed, it wouldn't show up on any page. If I bumped that number up, then it would show up.

After playing with it more, I discovered that no matter what my preferences were set to, 10, 20, 30... any post that was in a position that was a miltiple of that number was not displayed. So set to 10, every 10th post (not including the sticky post) in the forum was not displayed. same for 20, 30, etc... For example: When # of posts per page is set to 10, the first post on the second page under the sticky post should be "Web log analyzer for 500 errors". And the first post on the third page under the sticky should be "Hugo's other audio business?" and on and on. But none of those posts are actually even there.

I think it must have something to do with the way the sticky post is implemented. After the first page, it's somehow taking the place of the real first post for each subsequent page.