problem with regulation system

hi
I don't know if I am in the good place but when the regulation on my site start (300 people) I see in the rapport a lot of messages like this :

call_user_func_array(): First argument is expected to be a valid callback, 'imce_access' was given dans /www/htdocs/includes/menu.inc à la ligne 452.

I have white page too on the site and after a few minutes, the site is back when the number of people is decreased

is it a problem in IMCE ? I have set IMCE in module page and check the checkbox for regulation