Thanks for your thoughts Bjorn. The database is actually fine, and works well for the admin siteaccess - the problem is when using the file.ini.append.php in the front-end siteaccess. Unclustering and removing the file.ini.append.php works fine, but doesn't provide the solution I'm after.
eZ Publish is incorrectly using DB connection details from file.ini for ALL DB connections, rather than just for media/content-cache etc. What I want to know is, has anybody else experienced this problem?
This is odd. The clustering storage engine has nothing to do with the all the other eZ tables. I can`t imagine what side effect could cause this. DB connections are definitly seperate. I havn`t heard about a bug like this in the past.
Please already report for the others your PHP version and eZ version. So far i hope you use latest stable of both.
If you have found the cause on your own let us know about it.