A very serious bug slipped through in the latest release of Joomla 2009.07. One of the installation scripts had broken authentication to the MySQL database which results in this error on installation:
Database Error: Unable to connect to the database:Could not connect to MySQL
Many thanks to Janadmin who first reported this.There are absolutely no excuses for such a serious bug slipping into a release. We'll be changing our testing process to make sure something like this never happens again.
Meanwhile I've unreleased Joomla 2009.07 until we fix it. We're working on that right now.
Apologies to anyone who has been effected by this.