It seems that since jitspoe has updated SMF it has been driving me absolutely nuts that I can't see
every unread post on the forum. The 'Show all unread posts' link has been replaced by the 'show unread posts since last visit'. I'm usually not able to read all of the new posts in one sitting, and I was constantly finding myself missing lots of topics. Then I found the link to the 'All unread posts' view, but I constantly hit the 'show unread posts since last visit' link at the top/bottom of each page which brings be back to where I started.
After dealing with this for a while I've broken down and wrote a script to change everything back to they way I liked it. You can install the Greasemonkey script
here if you'd like.