I figured it out. It was a dumb mistake on my part.

I downloaded the full source version and made the mistake of opening it as a web site via Visual Studio 2005. The app ran perfectly and after playing with it for a while I made a minor change to the login.ascx.cs code. On rebuilding the web site, no matter what I did, the yaf.dll was never updated.

My mistake was in opening the app as a web site rather than a C# project! Visual Studio 2005 will not create or update a dll for a web site. It needs to be a C# project. You can either create a new empty C# project and copy all the yaf code into it, or just open the yetanothherforum.csproj which comes in the zipped download.

Hope this might help someone else avoid my mistake.