Hi Jerome,
Now i'm trying to setup brand new joomla + hikashop installation to see what will happend. If problem persist - i can send you admin password to help me to investigate the problem.
As additional information i can tell You that during exection of code, i can see for a parth of second that some parts of something like menu is displayed in the left of page, and after that the error is showing. No mather how deep i set debug level in server onfiguration tab of joomla - no additional info is displayed.
As attachment is screenshot of error page
On the new installation of joomla and hikashop everything is OK.
On the old one, i have uninstalled all 3d party extensions but the problem persist. The problem is only when creating hikashop product or category.... Everything other in hikashop running well.
Regardas
Kiril