SQL Server 2008 Installation Fail

I was setting up a SQL Server instance on my co-located server, but a series of events led me to uninstall it and reinstall it a few times. The final time through, it detected the original reporting services database, so I cancelled the installation and deleted the SQL Server folders. At that point I spent the next hour or so trying to make SQL Server get past the setup bootstrap installation.

The setup program told me everything was okay before it began the installation. The problem was, the installer just disappeared in the middle (after entering the key, before requesting usernames/passwords): it threw no error, the installation logs said everything was okay, there was nothing in the event logs.

I tried rebooting, but that didn’t work. I tried deleting the registry entries, but that didn’t work either. I checked everywhere I could think of for remnants of SQL Server. I then thought that maybe I dirtied my key with all my install attempts, so I tried to install the developer edition: same problem.

Then it occurred to me to check Programs and Features.

Sure enough, the setup program was installed, and it was causing the installer to fail. Uninstalling this fixes the problem.