I recently implemented Forms-Based Authentication (FBA) in MOSS 2007 and had it working great. Unfortunately we had to reinstall the system and I actually had more issues getting FBA to work correctly on the reinstall than I did the first time. It turned out that the issue was mixing different implementation methods that counteracted each other. The simplest way to configure FBA is to edit the machine.config file on the server (%WINDOWS%\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config) and change the LocalSqlServer connection string to the ASPNETDB user store or other database with the user information. This takes advantage of the pre-configured AspNetSqlMembershipProvider and AspNetSqlRoleProvider in...