It looks like you are trying to open the DB editor before the installation is completed. I would follow this topic in the wiki...I know you have already done this, but do it again to get a fresh start point.
http://code.google.com/p/open-media-library/wiki/InstallationProblemsThen download the 2 server install parts and run part 1. This should put both files into a single installer and allow you to do the install. Once the installer is completed, you should be prompted with the post installation wizard. Go through those steps and see if everything finishes successfully.
I think I had the same error when I was doing my installation and I just had to follow these steps to make the installation work correctly.
This is normal behaviour when upgrading to a newer version or reinstalling but in some cases when a previous installation went wrong or a completely clean installation is required look for a file called settings.xml under C:\ProgramData\OpenMediaLibrary\ and rename it to settings.bak. Try to reinstall.