I have an installer that installs an app that I've developed and a copy of the MSDE. The problem that I run into is that the installer doesn't remove the MSSQL$INSTANCENAME directory on uninstall (obviously, since I'm adding files there) and it won't reinstall if the directory exists. I set up a custom action to remove this directory on uninstall, but for whatever reason, it doesn't always work (probably file-in-use issues). What I'd like to do is run something akin to a custom action on install to check and see if that directory is there, try and remove it, and if I can't, tell the user that they need to do it. My problem is that custom actions run AFTER the installation process. Any ideas on how to run this check before the installation? I've used Orca (nominally) to edit the MSI file, so I'm comfortable doing that, if necessary. If there's a KB article, or any article for that matter, that I've missed, that would be great too.