OK thanks Till,
This time I set up a new site in ispconfig and checked all the boxes accept PHP Safe Mode and extracted joomla 1.0.7 eCommerce to the appropriate web folder and started the installation.
The first page confirms that safe mode is OFF.
The install goes well and I can log in to back end as administrator but cannot access phpshop when i go to view my site all I get is a blank page.
If I install joomla first and then phpshop I loose the front end but can log in to the back end.
Also in the PHP.ini safe mode is OFF.
I know very little about PHP and even less about CGI.