Did you try in private browsing ? Maybe delete your cookies.Is there a setting that keeps the sidebar hidden and the forum in it's wide setting.
Every time I click on a link or refresh the forum, the forum shrinks and the side comes out. It's really frustrating.
We've looked at a variety of solutions for this but it is unfortunately not possible to solve without incidentally hiding the "Report Ad" link. Since that's a pretty important feature to keep, we decided to leave it as is.I had the same problem and just grew to live with it.
The ads constantly shifting size and refreshing on desktop needs to be fixed too. It causes the page to move up and down randomly which is very annoying.