This week on a Drupal based website that I run I encountered an issue involving the combination of the Advanced Forums module and PathAuto. To start I'll say everything worked just fine initially. It was as I was trying to tweak things I broke it and I had a hard time finding the solution. Hopefully, if someone Googles about the problem in the future, this post will show up telling them what I did wrong at least.
PathAuto creates URLs for content (including forum postings) for Drupal automatically. So rather than seeing http://mysite.com/node/34 you will see http://mysite.com/content/Title-of-my-post. Because forum postings are nodes in Drupal, just like a blog entry or a static page, the default settings for PathAuto puts "content" in the URL like in my previous example. For the forum on this website I wanted the URL to be in the form of "http://mysite.com/forums/Title-of-post". When I made that change, the forums were broken.
First, if you want to know how to change the settings for PathAuto here it is: Go into Administer -> Site Building -> URL aliases (this assumes PathAuto is installed and activated). Go to the "Automated Alias Settings" and under "Node Path Settings" there are a number of fields for various nodes. For the "Pattern for all Forum Topic paths" I initially entered: forums/[termpath-raw]/[title-raw]. (Note, I said initially, go to down to find out why this is bad.) That setting will create URLs for topics/postings created by users in the forum. Additionally, there is a section for "Forum Path Settings" (which likely will be set already, but you can modify as you desire); this setting is for non-post forum items (like categories and individual forums).
Now about Advanced Forum. This is a module that puts some refinements to the core Forum module. One of the things it does is add a "Forums" option to the navigation menu list. It also adds hooks into the Drupal system such that any URL that starts with "forums" is intercepted by it and directed to the forums page. So based on my settings above PathAuto would create a URL such as: http://mysite.com/forums/First-Post. If you go to that URL, Advanced Forum grabs it because it starts with "forums" and sends you to the forums page rather than the actual forum posting.
The solution? Set PathAuto to use something other than "forums". In my case I took off the 's' so that the first setting I talked about now reads: forum/[termpath-raw]/[title-raw]. Now all is well with the world ... well, with a very small part of the world that involved that website's new forum feature.