Dear Victor, 
since we have made an update to the newest version 4.3.7 (from an older version 3.5.2) on all sites are showing an error message on the top, where Jlex Review is used. Take a look at: http://www.sondageremunereserieux.com/avis/toluna
You can see the following message:
JUser::_load : impossible de charger l'utilisateur ayant l'ID 1993
translated in English: JUser::_load : unable to load user with ID 1993
I know the reason for, because the user with the ID 1993 is deleted (he has canceled his acoount). Now my question, how no longer shows the error message?
Right, not the reason we would prepair (manual delete all comments from non members longer), only to show this error message on every site. Do you know, how we can stop this?
Thank you and kind regards, Evgenia