I rebooted as suggested but same problem. This led me to try full install on a brand new box but instead of using ISPConfig v2.2.5 I used v2.2.2 and everything installed OK. I then removed ISPConfig from my problem machine and reinstalled v2.2.2 and success, everything so far is working. I have created 2 clients and 2 sites and so far they are behaving. I am yet to install Joomla (my original problem), I will do that tomorrow. I will let you know how I go.
The only constant thing is change..