[sabret00the]

if you need a system outside of vBulletin to turn your forums back on, then add the query to a real cron job instead of a vBulletin cron job. simply add a query to the end of backup script to flag the cron job to turn the forums back on.

i.e.
Cron runs backup -> backup turns forums off first -> backup back's forums up -> backup updates a db table to notify cron job it's finished -> cron job runs every 15 minutes to see if it should turn forums on -> cron job see's flag and turns forums back on.