I've never encountered this problem before (except for this morning), but it is a problem relating to a particular thread.
On the "Writing Exercises Restart - Week Three" forum thread (and only this one), the sidebar will disappear fom the side of the screen, and appear squished at the bottom. The bar indicating who is online will then also be squished inward as a consequence. I don't know if this a real problem, but I figured that I might as well report it.
