General help

Thanks Petr, the strange point is that phpinfo (that we may call from Moodle) does display that we are using the release 5.3.16 or the release 5.4.6 according to the setting done in .htaccess, and everything else is fine (with php 5.2, we would already be in trouble during installation, according to some others posts).

On the other hand, I know that if it is needed to launch a script (as for instance the admin/cli/cron.php) directly from the server (not from a remote computer calling our web site using an internet browser as Firefox, but for example as a cron task or from a putty window) then there are some configuration problems.

The point is that we are using a "shared hosting service", not a dedicated server. We do have a possibility to choose the php version and to set up some settings thru the use of a .htaccess file located at the root of the moodle folder, and this will work if a php page is remotely used from another computer (using an internet browser), but we can't control the settings that will be used when a php script is directly used from the server, as for instance within a cron task, or using a direct command line (thru putty).
But I don't know if this may explain the error that we get here.

(it could if a moodle script was calling another moodle script thru a specific kind of system call (?), possibly using another instance of php or others settings of php but this seems quite strange...)

I don't know if the fact that the "magic constant" __DIR__ is not defined inside www/moodle/lib/dml/moodle_database.php may help to understand what is happening... Thanks again for your help !